Congrats on 3 excellent choices! I would encourage her to think of it this way: if she had only gotten into 1 of these 3, the choice would be easy and she would not be worrying, she would be rejoicing that she got into 1 of these fine institutions! In other words, she can’t go wrong.
Each school has a different vibe, and fits different goals:
SMU is locally prestigious and will be within her current comfort zone in so many ways. Choosing something known and comfortable is a fine choice, going to college is enough of a transition in itself. If her goal is to eventually settle down in Texas, SMU is a great choice. She can still “get away” with study abroad etc.
Columbia and Northwestern have national prestige. They will both be a bigger intellectual and personal stretch. She is 100% capable of doing this, but at first it will probably be a bigger adjustment than going to SMU. They will also both be more of a financial stretch. I went to college at a private school with a lot of rich kids, and it was a culture shock at first. I had to learn to say “no” to a lot of things like ordering in pizza, or going out to movies etc. It took me a little while to find the kids on campus who were more working class like my family. She may need to stay on campus for small holidays like Thanksgiving break. My own son goes to college in NYC (at a different school) and since we are not a drivable distance, he stays on campus for little breaks like that. Luckily some of the other “from far away” students also stay on campus, so he isn’t lonely.
If she decides she does want to eliminate SMU, I would not overthink the difference between Northwestern and Columbia, I would just go on gut. Columbia is smack in the middle of NYC, either you love that or you hate it! Northwestern is more suburban, more polished and calm. Both have excellent academics and connections, so for example Northwestern supposedly having a “better” journalism department doesn’t matter. Just pick the environment she would rather live in for 4 years!
I understand about the money, I know it’s a stretch, I was in that same position when I was a college student. But there are ways for her to supplement. She can work hard each summer, and many places will hire temporarily for winter breaks. And the one secret of expensive cities like Chicago and especially New York is that babysitting is also ridiculously expensive! Especially if she is babysitting Friday or Saturday nights she will rake in the cash.