Stepmom torturing my dad

My dad got married again after 5 years of my mom's death. The women he married was single and was living with her mom all alone for almost 10 years. She is having some mental condition and the day she entered our house everything became a mess. She hates socialising with other and used to fight with cousins for no reason. Everyone in my family gave her many gifts, my dad always take her for trips but then she still harass my dad and always create tension in the house. Her mom also used to inject all sort of venomous advices into her head and the same will be taken out when my dad comes back from work. He is 64 and does all possible things for her to make her feel happy. Lady is 51 years old now, couple of years ago her mom passed away. They both used to mentally torture my dad daily and would threaten my dad of committing suicide. She never gives peace to him and none of our family members visit our home because of her behaviour. She always says that she is tired, have pain in the body but when my dad tells her about visiting hospital, she would get agitated and starts abusing him. Day by day it's getting worse and I am concerned about the health of my dad. The lady does not have a home nor she is in good relationship with any of her relatives. I am 32 years old and I fear that my life will be at risk because of this lady. Please help us 😔