The only plausible reason I had for Carl not shooting her, was that she was his mom and he couldn't do it. I hope he really did though. But however of a crappy mom she was, she was still her mom. I say I would have no problem shooting a family member if the ZA happened and they turned, but I really wouldn't know until it happened. I'm sure it would be hard. I do think she died, but the way it was done, I feel it left some stuff open if needed (just in case the writers wanted to throw us for a loop). Like zombie Lori walking out if the walkers invade the prison, like in the comics. That walker ate her pretty quick, bones and all, if not.