My mother was not too pleased with me getting an 5year old BP almost 3 months ago.. I'm an adult who pays rent, so her only true gripe was- "YUCK!"
It took 2 weeks for my BP to win over my mother's heart. Now she tells me how beautiful she is, and asks me to show off the snake when her friends visit.
My best advice, is to bring your mother to expos and pet stores so she can feel more comfortable with them. From there, all you can really do is cross your fingers and hope she likes them, or at least tolerates them
I wish you luck!