What should a son do if his father oppressed him and his family, but now asks for financial support in old age?

My neighbor requested a Fatwa (Islamic Verdict). The question is that his father never assisted him during his life. He did not bring him up well, nor did he give money to maintain the house, or he would give it with difficulty. He used to beat his mother, his sister and him. He also used to curse a lot. He got married to another woman and didn’t do justice to his first wife. He oppressed them for his entire life. Now is second wife has left him. He is alone. He tells his son to take care of him (financially) and serve him. Now his son does not want to take care of him or serve him because his father oppressed them for his entire life. He never gave his son money for marriage, nor studies. My friend saved up some money from working to get married. Now he has a son and he is responsible for four people. He also has to maintain himself from his work. Please tell us what he should do. He said that his father is telling him, “Give me all of your earnings and I will maintain the house. Just leave your wife, son and mother with me. You remain alone in the hostel.” He wants his daughter-in-law and his first wife to remain serving him. His father spent his earning on his friends for his entire life and disgraced his family. Now he is very concerned about what he should do.