maintainence from daughter under section 125 crpc

Hi, My father has put a case against my mother and me asking for maintenance,while he did not take care of any of us. I have a younger sister as well and my mom is a teacher in a govt school. She had to take a step 10 years back to separate from my father as he ill treated and abused us till I was in 9th standard.Also his family was the same, used to torture my mother from the first day of their marriage. My mom wanted to us to live peacefully and get a good life and he was always after us and used to embarrass us on the roads also. My mom somehow with help of her family and taking home and personal loans and education loans, educated me and my sister. Now that I have started earning, he wants maintenance from my mom and me both. Also, he's asking on a basis of cancer that he had 20 years back and got treated and is somehow getting fake documents from his doctor friends. Also, he is living with his parents and they have a joint property(mom and dad) where we were living and my mom invested 80 % in it. Now my mom is paying home loan for the house she bought with family loan, and personal loans. She hardly gets any money left. I am married now and my younger sister is still studying. We are somehow managing to a live peacefully as I pay fees for my younger sister. We have gone through a lot in childhood and again he wants my address through the court after that I am married. Mom has asked a lawyer and he's taking 1.5L, but not at all supporting my mom and my dad is faking when he comes in court that he cannot speak and he wants 20k from me and 20k from my mother, while we earn in total 70K. He also warned my mother outside the court that he will take the other house which she's paying loan for and is on her name. This is like a continuous torture she has been going through throughout her life. She is 51 yrs old and only 10years of her job are remaining. My father told in front of the court that he doesnt want divorce even after separating for 10years. They had a mediation court dates in which it was suggested that they should sell the joint property and take 50% each and mom can put some amount in FD for him as maintenance and she agreed and also on divorce, but my father said no for divorce and 50%. he wants full house and also maintenance.He didnt had to do anything in life, except producing us. He never cared about us, and now that we somehow living, he is again trying to harass us. I want serious advice and help if someone can. It seems females in this country can be harassed as much as possible and men can do anything they want.