First of all, why does Mom know this information, since she's a ghost, and has not returned to life in a human form? And secondly, if she knows this information, why doesn't her child know it? Where does the knowledge come from (hint: the writer).
This is a line of dialogue that didn’t need to be spoken, because it is obvious from the action on screen what is occurring to the Old Crone in Josh’s body. But to have two ghosts discuss this matter in such normal conversational terms is a miscalculation of the highest order.