Before MAD: Zombi
Bambi's Mom tried to go to the shelter with her son Bambi to run away from Man, but Man shoots her to death, making Bambi an orphan for good, The Great Prince of the Forest grieving the loss of Bambi's Mom.
When Bambi sees the Tombstone when his mom was buried in the graveyard, Thumper, Flower and Bambi saw Bambi's mom raised from the dead as a zombie to scare Bambi, Thumper and Flower. As a zombie, Bambi's Mom seeks revenge against Man and scares him with her zombie noise, Bambi, Thumper and Flower manage to defeat Bambi's Mom and Man by locking them in a door, she presumably devoured Man alive as she was locked in the door along with Man.
Bambi's Mom was originally the heroine Great Princess of the Forest, but in a parody, she is portrayed as a vicious zombie with an antagonistic role.
Man was seen as the main villain in the two movies of Bambi, in MAD: Zombi, Bambi's Mom is portrayed as the true main villainess.