daruler,
I think anydaynow and AKAtude gave you some good advice to help show your mother the good that AKA does in the community. I bet there are members of your church that are AKAs that your mother could talk to. Look for the tags on the cars in the parking lot!
There is one place, however, that I disagree with them. If you are still a college student, I would not join a sorority behind your mother's back or without her blessings. If it is in your heart, Alpha Kappa Alpha will be there after you graduate and are more independant.