You can make another hide out of a bowl or plastic container you may have around the house. an old cool-whip bowl or a black take-out plastic bowl would work. Cut out a little door and go over the edge of the cut-out with a lighter to smooth the plastic a little, and there you go. simple and cheap.

If you need to increase the humidity, you can get a spray bottle and mist some water in there a few times a day. Depending on how you heat, the humidity could stay well, or evaporate quickly.

the Frozen mice... if she refuses to eat... some will say throw it away, others say you can keep it for a day or two. Being that you can get them for about a dollar or less, I'd probably throw it away to be safe. If you go the pet store and they have frozen mice, you'll want a frozen hopper mouse. that should be a decent size for your snake if it's as small as you mentioned above.