plug up all holes/gaps coming through the walls and foundation, making sure all floors have no gaps from below, trapping the mice that are in there (peanut butter on snap traps works well, put a little peanut butter on top of the trip pan, but put even more underneath it so they have to work at getting to it). check traps in the morning and reset before night if you don't want to leave them out all day. place traps along walls where they run.
Honestly, you already know the answer to a mouse problem.
Multiple cats.
I am not trying to be funny. I have a corn field in back of my property. When I was down to one MALE cat, I had mice.
I have 4 female cats and one male cat right now. They are inside/outside kitties.
NO mice in the house, just in the barn, when the horse feed is, and in the loft.
My metal back house door wasn't put in right. The frame has gaps and I can assure you ANY MOUSE can and does get it in. WE just never see them.
Mice will invade you kitchen. They run through your flatware drawers and they have no bladder and carry diseases.
Unless you are inSANELY allergic, I suggest that you pick up a couple of litter mate kittens and raise them up.
I was never a cat person until we got them for this 5 acre property.
Cats can and often are Very affectionate.
Just sayin...
A friend of mine got some help from one of her cats recently. She was sitting on the couch watching TV and both of her cats were sitting in front of the entertainment center watching something (other than TV) for like an hour. She thought maybe there was a spider under there. Anyhow, after an hour of patience, one of her cats came forward with a mouse in his mouth!