Sadly I have a SIL who is deathly allergic to cats. I had someone just recently tell me that dryer sheets keep mice away in their vacation house when they aren’t there. I hate the way they smell, but it might work for you. We usually get a few mice every winter in our house. Have yet to figure out how they get in.
We had mice in our old house and we also had a cat. She definitely could hunt and we had to keep an eye on her outdoors. On rare occasion she found a mouse indoors and more than once she captured small rodents outside and wanted to bring them in. I also learned what “playing possum” looked like thanks to her - thought she killed a baby right outside our back door until I realized its tiny chest was moving.
One day I pulled out a kitchen drawer all the way and found a supply of cat food stored behind it. Where was Tabby? Probably upstairs sleeping on our bed while the mice were raiding her food.
Nothing will deter them from coming in, not even a cat. In the fall, when they are looking for a warm place for the winter, we get a few in the attic. The “rule of thumb” is that if your thumb fits into the space, so will a mouse.
They rarely find a way into the inhabited part of the house, but occasionally one does and our cat makes short work of it. While I appreciate his diligent efforts, nothing is more horrifying than to come downstairs in the morning to a massacre. I don’t understand why the mice still come in knowing that it’s a sure death - and a slow painful one at that - it’s clear from the aftermath that he plays with them until they die.
Here’s another vote to “hire” a cat.
Our 15 year old cats keep our mouse problem under control, but do not eliminate it entirely. Just be aware that if you use cats to control your mice, those cats will occasionally present you with thank you offerings, sometimes on your bed in the middle of the night.
But- having a cat means dealing with all of the care that comes with it. Litterbox, cat hair, food, preventive vet visits… Sounds like a lot of work for a busy college student.
We get mice. DH is deathly allergic to cats though I would love one. I found the electric traps powered by batteries the most hassle free approach. I will try peppermint oil as well.
DD is using peppermint oil. It worked up to now but today she noticed a mice running into her dorm room. It’s run away immediately, but I guess we have to think about something stronger then peppermint oil now. How good are those electronic repellents?
I’ve found the electronic things work for a little while, then lose effectiveness. Maybe the mice just get used to them. I like the JAWS traps, so easy to set and use, and re-use. I have a relatively new house, and I have a cat, so no mice there… but I keep one trap in my office and one in my car (yes, we have lots of mice in our cars out here in the countryside. I get one or two every week in my car…) . Have used lots of peppermint oil in the car. Seemed effective for a brief time, but now the mice don’t seem to care that the car smells minty fresh…
I’d be surprised if the dorm or student apartment allowed a cat.
I had mice in my apt when I was in Gard school. It made a dime sized hole under the sink to come in. When I found it out, I plug the hole. Next day I checked to see how the hoke was holding up. A mouse made another hole right next to the one closed up. I closed up that one, too. On the third when I looked in, the mouse had just completed making another next to two previous holes and was looking in. Nice to meet you, Little guy, Come into my parlor.
Mr. keeps a large Rat Zapper in the garage just in case. He does not want any mice to make nests in his X like they did in his truck. Although that truck was an animal magnet - once we heard howling from the garage and found a giant orange cat wedged around the engine! The cat must have snuck inside the garage when Mr. opened the door for 5 minutes to get the garbage can out. 
The truck was manually pushed out of the garage on neutral, and the cat decided to get out on his own. Disaster averted!
If she can figure out where they’re coming in, she can block the hole with Great Stuff or another foam. It won’t last forever and they can eat through it, but it will block the route for a while - she can keep checking and apply more foam as needed.
About moustraps, no way I’d touch the trap after it worked. In college, when we occasisonally had big bugs, we went and got a bio major to tackle them.
Old dorm building has mices this time of the year. They come under the door from other rooms.
One of my achievements as a single-again middle-aged woman is that I have conquered my fear of dealing with mousetraps. I still find the process distasteful but you do what you gotta do.
I just gave the one(s?) in our house a choice between kill and nokill traps. He chose the kill.
And I splurge on disposable kill traps so I don’t have to view the corpse. I’ve had pet rats and mice.
With the Rat Zapper, you just shake the stiff mouse corpse into the trash can. No blood, no gore.
Eeew.
They can squeeze through the tiniest opening. Unfortunately, some I know use bait the mice eat and they exit this life elsewhere. No idea if a dorm allows that. (It’s important not to spread it where cats can’t get at it. Either a contraption that only mice can enter or in some place in the dorm room. Be careful.)
I’d seriously have to move. At night I’d be convinced they’d be crawling all over me. They carry disease as well. I imagine this place isn’t cheap either.