my sister in law tricked the ghost and became her servant

This is the story of three women who used to go out every morning for a walk, one day they found a monster from a river and he said that I will eat you if you want to escape from me, then you throw something in this river if I find Brought it, I will leave you, if not found, I will eat you. Seeing that truck, my sister-in-law dodged that monster and made her a servant.