Original sentence: He also orders Norma Bates' body to be exhumed, just to prove to Norman that she can't be the one haunting him.This is a major plot hole in the story because it is revieled in the first Psycho that Norman saved and preserved his mother's body, while a weighted coffin was buried with no body in it
Edited sentence: He also orders Norma Bates' body to be exhumed, just to prove to Norman that she can't be the one haunting him; his mother presumably being buried after the events of the first film