B - if you're sure it was a genuine case of rape, but only if it bothers you so much it is consuming your life.
I would avoid C - the idea behind 'rape' is becoming increasingly cloudy. What starts as willing sex, can change for whatever reason, but men, generally being stronger and dumber in the bed, don't know when to stop. I know rape is always horrible and should never really be protected, but there is a difference between attacking a woman from the onset and raping her against her will, to a woman changing her mind mid way and perhaps the objection not being clear enough and hormones taking charge.
Neither is defendable, but attacking a woman for sex is far more heinous. Of course, I don't know the full story. Yet I would never wish to start a smear campaign or cause too much attention. While you make sure it is known that he is a rapist, you also proclaim that your friend was raped. There will always be people out there who will think just as badly of her, or will never know how to talk to her again. Seems like unnecessary damage.