I would have said something much more snarky. But then, I have no filter when it comes to trendy dietary choices. (I’m looking at you neighbors who won’t eat our Christmas cookies because you all of the sudden decide to go gluten-free, even though none of you are gluten sensitive or have celiac disease.)
I think your husband was fine. But I would add a large container of hummus to the table. That would be great on a bagel! Then, forget about it!! 
The vegans I know all seem to have difference preferences and in many cases different “rules”. It’s used as more of a catch all phrase than dining guidance by many. So I’d need more info about what vegan means to this person if I wanted to give her food options, which means more digging and work on your part. Can the catering place just put together a big salad and some dressing options (maybe something “vegan”) and let it go at that?
While some people make exceptions in their veganism, for instance eating honey, a food which is not strictly vegan, or making exceptions for trace amounts of dairy in otherwise vegan foods, it’s usually safest just to go full vegan. Peanut butter is vegan, so that’s another readily available option.
Instead of “I hope you’ll find something” he should have told her what options would be available.
Personally, I’d make sure there was something there she could eat but he could at least give her a head’s up that she’ll need to eat before she comes or bring something.
@BuckeyeMWDSG As a mother of a child with food allergy, I can’t tell you how much I appreciate someone who does that. Usually she has to bring her own granola bars or just go hungry. Being included in the meal on any level is much appreciated.
I do think it was a bit rude. I always ask my guests if they have any allergies or diet restrictions. Each of my daughters has friends who are celiac and vegetarians and vegans. I always have a few boxes of gluten free mac and cheese and/or pasta in the house. We always have hummus and salad fixings. It really is not difficult to add a salad and a container of hummus to a buffet. I always want people to feel welcome in our home.
The guest should have said something like my diet is vegan now, would it be OK for me to bring a dish to share? and then the host could have either said, yes of course, bring what you like OR the host could have said - well we are having ordered in trays for everyone else may I see if I can order a vegan tray for you? Everyone could have handled this in a considerate way.
Years ago, I remember attending a Catholic mass that was a special event, so a lot of non-catholics were in attendance. The priest said he would serve communion to the Protestants if they wanted it (technically priests are not supposed to do so). He made a remark to the effect that in not doing so, it would be like inviting people to his home for dinner and then not feeding them, and that would be rude. That story has stuck with me for a long time.
As others have pointed out, you are ordering, not cooking, so would it really be such an inconvenience to have a small vegan dish available? As for the fridge stocked with drinks, are you sure there is not room for a small container of something?
I think you need to ask yourself, is it that you really can’t accommodate her? or you don’t want to accommodate her?(There’s a difference between can’t and don’t want to) or are you digging in your heels because you find the vegan thing weird and and are annoyed that your sil called your DH out on his comment?
If the answer to the first question is yes, then so be it. But if you are answering yes to one of the other two, then it’s best to provide her with a little something she can eat.
^^^^Bingo. She should have told your husband about her dietary restriction and that she hoped it doesn’t mind, but she was bringing a dish. That would have not made your DH feel like she was telling him to go do something just for her and that he won’t wonder why she’s not eating. That’s gives him the option to go by something for her without feeling like he was told to.
^^This. I would tell her the menu and suggest she bring something that would work for her. Just adding a vegan option like hummus is fine unless she hates that. If this is a voluntary dietary restriction there’s only so much I’d do.
I also have celiac. It’s not a choice for me to eat gluten free and it’s hard. I struggle with when to mention it. Church dinner - I just eat what I think I can or not at all. Cocktail type thing - eat later, no one paying attention to how much you eat. Someone’s house or sit down dinner - more complicated. What is there is nothing I can eat? From host perspective I’d hate to see a guest sit there with nothing to eat. If I don’t say anything and then the whole meal is lasagna and salad with crouton, etc am I going to embarrass the host when I sit there not eating.
I also realize it’s hard for people who don’t deal with it on a regular basis to truly understand all the details to celiac. I would have the same trouble figuring out if something were really vegan, so I don’t think inviting the person to provide something is a bad thing.
I was vegetarian for 35 yrs and vegan for 1 yr. It was always uncomfortable to mention my dietary
choices and it was often even more uncomfortable to say nothing which led to the host being concerned.
We entertain people with different choices frequently. A vegan at a dinner is a challenge but with all of
the available foods quite doable. One issue that is a constant is everyone will want the vegan or vegetarian
foods. Happens over and over. So if you buy hummus,for example, make sure there is enough for all.
As a hostess, I absolutely want to know if someone has special needs or even tastebuds. I sure
do not want to prepare a lovely meal and then find out “I do not eat that”. Why? Because I want
to be a warm and generous person even when it is inconvenient and annoying.
I would either have an offering for her or text and ask if she can bring a vegan dish to share.
My own issue is that I am poultry intolerant and suffer for days if I eat more than a few bites of
whole eggs or poultry. It is a pain and my close friends know so that is easy. Being invited to a new
friends home and having them notice that I am not eating their chicken entree----just no
good solution. Tell and
I am in the rude camp. You invite people and you accomodate their dietery need. You don’t need to turn everything vegan, just one or two items. It’s no big deal to have an item or two for a vegan. You don’t have to make it yourself. Stores stock them. It’s protocol people let their hosts know of special dietary need.
This could be one of those cases where real words spoken (in person or over the phone) might be more effective than a text.
I agree with the others that the kind thing to do is to pick up a container of hummus and tabbouleh (all you still have to do is pop off the lids!) - it will make her feel loved and respected for her choices too.
But back to the text…if those couple words were indeed all she texted back…maybe she fully intends to bring her own food. Maybe this is her way of saying “please don’t be offended if I don’t eat the food you have”. Or maybe not. We don’t know from just those few words.
Same with the way your H text was received by her - as “we’re so happy you are still coming and there should be a think or two you can eat” OR a snarky response “oh, vegan??? Suck it up, what’s on the table is what we’re serving!”
While I totally understand where your DH was coming from, I agree he could have handled it more tactfully. Where I have a problem is for your SIL to call him out on it - what purpose does that solve other than to stir things up? Your niece needs to handle this sort of thing herself - she is a big girl now and her mommy really needs to let go.
I don’t think "“Happy you are joining us. Hope you’ll find something you’ll like” is rude. It’s an open statement, not “Hope you don’t come hungry.”
What I don’t get is making this into an annoyance. You do what you can, she adjusts as she needs. You’re not throwing this dinner for her (then it would be rude to not consider her interests.) But neither is it the end of the world to make sure something works. Seems she didn’t demand anything. And after all, it’s a religious holiday, a family time.
I was more ticked when my SIL watched me cook, then, at the table, announced she wouldn’t eat the main course. On another occasion, I regretted a new friend didn’t let me know she was vegetarian, in advance. I would have gladly shifted a side dish to avoid meat ingredients.
I think we try to roll with it, when entertaining others. It’s a good thing and the nature of being hospitable.
I vote that the host was very rude, the guest was not rude at all (she politely informed that she was vegan). And trivializing it into a “voluntary” restriction? Not eating pork is voluntary too.
I hate it when guests don’t tell me about their dietary preferences and then I find out they won’t eat a dish I’ve prepared lovingly for them. I have friends and family members who are allergic to various common ingredients, and if I’m inviting them, I’m always trying to make sure they can eat not just a single dish, but most of the stuff on the table. So yes, I do think it’s rude to invite somebody to a meal and then not try to accommodate their preferences - not to the point of making the whole meal vegan, of course, but enough for them to have a good meal experience.
Well you could reply, “Oh I wish you’d told us sooner, we’ve already ordered all the trays.” But I also assume you could call the company and say, “We just found out that we’ve got a vegan coming, can you trade out some of the ___ for a vegetable dish without cheese or dairy?”
I have so many friends who are minimally vegetarian, occasionally vegan and/or gluten free I always ask what they can or can’t eat. As someone said upthread - sometimes it’s as simple as having the gorgonzola in a dish on the side instead of ruining the salad. (I’ll thank you too, and I’m not vegan. I’m still mystified why my SIL does this to me every single time. She always acts totally surprised that I pull it all out.)
“Can the catering place just put together a big salad and some dressing options (maybe something “vegan”) and let it go at that?”
Catering orders for the holiday were cut off a week ago ( im sure if you don’t live in a Jewish area you aren’t aware that this is a common practice. ) if she’d told us before cut off I would have ordered roasted veggie sandwiches. Too late now. Cousin does not eat hummus or guac or anything " dip- like/saucy". When she was a vegetarian she would obviously have the cheeses plus kugel and deserts. Would want some sort of roasted veggie dish or bean/grain dish according to H’s sister. That’s not happening. If that’s rude I guess we will have to live with it.
I think it would be courteous to give her as much information as possible – including the full menu, the fact that it’s too late to make changes, and the setup of the event.
She might not want to attend if it’s a sit-down meal and she can eat almost nothing. That might be embarrassingly conspicuous. But if it’s more of a casual buffet, with people getting food at different times and sitting in different places, she might want to attend to enjoy the company but eat her meal before or after or bring it with her.