Mister Fandango wrote:
They just assumed she was dead because the only thing they found was her bandana.
...which was kind of a stupid assumption for Rick's group to make.
One: There were no remains at all, and from what we have witnessed over the earlier seasons, zombies do not haul bodies away like a wild cat, and there were no signs of struggle or a trail of blood from the area where the bandana was found.
Two: Zombies do not eat bone, so if Carol was attacked, and even tried to run before collapsing, her clothes and bones would have been discovered (by now) by Rick during his vengeful clean up of the prison. Evidence of this is T-Dog--he was attacked and his remains were found in the spot where he fell.
Three: the rest would not know the following, but Carol just as easily could have decided (or truly believed) the prison was overrun, so she found a way out of the prison and bolted for the woods. That, or the emotional damage of her T-Dog pact being broken in the most gruesome way was too much for her to deal with, so that too, led to her leaving the prison...maybe into the hands of someone.