Big Problem With My Friends?

I have these to girlfriends who are best friends cindy and maryThis is How it Started: cindy got a hicky from her boyfriend bob but blamed it on her best friend mary, saying she was pinching her neck When her mom saw the hicky. she said this so she wouldnt lose her boyfriend bob.Now cindys mom wont let her talk to her best friend mary cause she thinks mary is a and they both have "somthing" going on...my friend is really upset now and worried shell never be able to see her "best friend" what should i do to help out?( i changed the names)