I wouldn't really say Carol has become meek again. I think she's just come to the realization that she doesn't like how much of a cold blooded killer she became and wants to stop. But she doesn't know if she can stop, especially if she stays with the people in Alexandria. Hence why she's trying to leave. She doesn't want to kill anymore but knows of she stays then she would eventually be forced to kill to protect them again. So she's willing to go and take her chances on her own rather than be in that position.

Im not saying I agree with her reasoning at all, but it's not meek to decide you aren't going to kill in such a world. It might actually be the hardest decision someone could actually make.