It is a tough situation, and she really put Rick in a pickle by confessing. She should have denied and, no matter what Rick thought he knew, he never could have proven it was her.
Now, though, what is Rick (or the Council) going to do? For the sake of the social order of the group, you can’t have group members going around killing people willy-nilly. But Carol is a valuable member of the group and one of the “founding” group members. I think Rick is going to put this off for as long as he can, but I don’t see how this is going to be resolved without some punishment for Carol, be it exile or execution or whatever.
I think they’re about to get into deep trouble and Carol’s guilt will be put on the back burner. They might address it later, but they have to survive for now.
They wouldn’t execute or exile her, anyway.
I got the impression they had turned and Carol merely zombie-killed them in their cells and dragged them outside to burn them.......