Mental Harassment Of Parents Above 60 Years

My brother is 35 years unmarried staying with my parents. He is not earning till date but he keeps control on parents and ill treat and fights with them every day. He had not allowed my married sister to visit our place and locked all doors of the house. Even locks kitchen so that no one can eat. He is mentally torturing my parents and they can't even talk freely in his presence as he never leaves the house. This is going on for more than 10years and now the situation has worsened to an extent that he still continues with his everyday fights with my I'll father who has just been discharged from hospital after a month. He says everyone has to operate as per my instructions. Due to Corona, our business is hugely impacted by almost no income. And he has started putting restrictions on the food diet of my father stating that we cannot spend this much money on food items without no income. Always there is darkness in the house with us talking in whispers to each other otherwise he will start fighting.