Uh. If your BF is actually listening to her, you probably don't want to stay in a relationship with him, anyway, because you may as well be his side piece. If he lets her control him now, he's not going to stop just because you get engaged, married, or have kids. Not to mention that the fact that she is equating a drive under an hour long as being too far away means either she has a girl she plans on forcing him to meet and possibly date, or that he is her retirement plan. Meaning that she expects him, any spouse he has, and any children he has, to take care of her for free and unconditionally once she isn't actively working. Which is a fate worse than singlehood for most people.

If you're not married, she's not your mother-in-law. Also, tell her to get ******, her son is an adult and can date who he wants.