I gotta agree here. Mom's house, Mom's rules.
It wouldn't hurt to try to put together an informational package for her though. Maybe treat it like a homework assignment? Cite examples and sources and try to show her that smell and allergies aren't typically an issue with snakes. She may appreciate the time you took?
If ultimately she says no, you have to respect that though. At least you can keep them in the garage. I didn't get my first snake til I was out of my parents house, my father was absolutely not having a snake in his house. And I had to respect that.
Good luck!