My cousin is the victim of malicious slander, what should she do?

My cousin is an incredible beautiful woman with the allure like Scarlet Johnsson with dark hair. She is not young (in 30s )though her looks is that for the 20s. She went back to school for a top finance program with majority of the students are male. Those guys prey on women. They got every girl in the program except my cousin. My cousin would rather be isolated and do all group homework by herself than fall prey to these guys. Those guys then retaliate against her by spreading rumors that "she is a call girl, everyday looking for somebody to sleep with". "And she slept with every guy in the program". My cousine actually doesn't have anything to do with anybody there, and those guys make sure she is isolated so nobody really knows what she is like. And they would collude with each other whatever rumor they made up. And now she is even afraid to go out as there are guys campus trying their luck on her. Can you believe this is happening on campus? Will this destroy her career?