Mom (1990)

Call her mad, call her a monster, just make sure you call her once a week!

During a time when the city of Los Angeles is terrorized by animal attack style murders, a kindly elderly lady provides a nomad with room and board. It turns out that he is a werewolf and is responsible for the recent killings. He bites the elderly woman, turning her into a hungry werewolf. Now her adult son must try to prevent the both of them from doing any more harm.