As far as I can tell, you are both adults (you and your girlfriend) and are capable of making your own decisions. She should not try to manipulate her daughter into which decision to take. The few couples I know that married without their mother's consent, found that after marriage or having a baby, the mother wanted to be part of their life once again and started accepting the relationship.

also reject you. all mothers wants rich son-in-law. and rich husband for her daughter. (sorry' there are many mistakes in my English)

depend on you, guys. My aunt's daughter left her family to live with the man she loves. My aunt thought her boyfriend is a kind of bad man who dont have a stable job, gamble guy, not able to take care of the family...But finally, my sister moved out to live with him without my aunt's permision and they didnt talk with each other until my aunt got cancer and had to go to the hospital. You guys are old enough to make your own decisions. It will be wrong if you guys give up just because of her mother's opinion.