There is a ton of stuff you can do if you have allergies and want to have an indoor cat.

*Get a vacume with a hepa filter....if your mom has allergies, this will help her every day. Its an excellent investment if she's that bothered by them.

*Install hepa filters in your air conditioner

*Vacume and dust your house often

*Groom your cat, giving them lots of brushing and wipe baths. You can get these http://www.petsmart.com/cat/shopping...%5F34708.shtml at your local PetSmart. I'm going to pick some of these up this week for our furkids.

We normally use these:
http://www.petsmart.com/cat/shopping...%5F20138.shtml and they work really well.

*Get a shedding hook for cats. You'll see them here at PT, there's a thread right now all about it. It removes SO much hair.

*Don't allow the kitty in your parent's bedroom

I have both allergies and asthma and my maine coon sleeps on my pillow at night. (READ: large, furry cat) All this stuff has worked for me, and I've also developed an immunity to the cats.

If your mom has allergies, she's most likely taking something like Allegra. That works for cat dander as well.

Good luck! Let us know what happens.