How Can My Friend Handle Her Psychopathic Boss Who Makes Her Work Late?

One of my friends is working as an officer in a cooperative organization. Her boss is a psychopath and mentally tortures her by assigning various tasks. She is a mother of a one-year-old child. He plays his crooked games to make her stay in the office late at night. He is very arrogant and yells loudly. Whenever he gets a chance, he diligently makes fun of her. He even asks her to change her work unit and go to other units with her one-year-old child. What could be done to deal with him? He is not normal. Once we offend him, he will go to great lengths to make her life troublesome.

Hi, She can be advised to write about the behavior of the boss to the top superior and ask for their intervention. Is there any personal motive behind his behavior, like personal vengeance? Were they known to each other before joining the cooperative organization?