I really don't think she's still alive. But then, in The Walking Dead, I just kinda assume that nobody is still alive.
I'm having trouble working out the radio thing, though. It isn't somebody in Savannah who has been talking to Clem all this time. First of all, the radio can't possibly reach that far. Secondly, the second radio was never in Savannah - it was with Glenn. What happened to it after that? Does anyone remember? If somebody really has been talking to Clem all this time, they've been doing it from close by.