that's kind of cruel. as a tomboy, I find it essential to hang out with guys. they keep you from being too girly and prissy. i can see your mom's reasoning with the boyfriends and everything but honestly, I think it's a better idea to let you talk to them since it'll let you understand them if you befriend them. plus, your mom needs to have more faith in the other gender. I hang out with more boys than girls (just as friends, honestly) and it's so much fun just to talk and crack jokes. honestly they won't go on about stuff that is of no interest to you.
but to answer your question, no it's not right, I don't think, but I can see where your mom is coming from. I'd say it's normal, just cruel. like telling your kids not to watch TV shows or not to talk to your friend anymore because (s)he comes from a different family?