My father is deceased and the rest of my male relatives live overseas. What are my rights within the Islamic religion if my mother rejects the person I wish to marry for no valid Islamic reason?
If your father is deceased as well as your paternal grand father, you don't need to obtain permission from any one for your marriage. No doubt, you must keep respecting and serving your mother, but her permission is not compulsory in your marriage. Try to explain your situation to her with high respect to her, but the rule of Islam is above every one.
Wassalam.