my mom didn't want me to have a snake in her house either. so a few years later i went out and got a couple pet tarantulas... she didn't even notice when i got the snake =D
but to my advantage i'm away at college now, so my pets only come home for limited time over long breaks. interesting enough though when i am home my mom always has to look at all of them every night. she says it's to make sure none of them got out, but i think it's more of her becoming more interested in them hah.
so i guess in my ramble.. i'm saying find something that scares her even more and make the snake pet a compromise.