Legal right of wife over his husband property

I need to understand the legal right of my mother has on his husband (my father) property. My mother and father is separated for more than 30 years but they haven't gone for legal divorce. Currently my father is married to another women and having two offspring - one son and one daughter and they live together in a different property (not the property I am seeking advise). The property I am talking about is a two floored house (say property A) - with basement floor in name of my father and top floor in name of my father's second wife. Also this property was bought by my father and was not inherited. Currently my step brother and me renovated the property A. The basement floor I have renovated solely with my expense and my step brother built the top floor. I had built the ground floor and make it in living condition so that my mother can stay, bearing all the cost including the common cost and specific cost for the ground floor. Right now my mother is staying there. But recently due to altercation and family feud - my father and step mother is asking my mother to leave the property. Also I am not in town and due to recent COVID-19 situation even can't travel. Few points worth mentioning: 1. My mother and father are seperated for more than 30 years but not legally divorced 2. My mother was living in this property for more than 30 years including my grand mother and grand father (my father's mom and dad) who are no more 3. For more than 20 years my father was not bearing any living cost of my mother - not a single penny 4. We are three brother - I am the youngest. My elder brothers don't stay with my mom and some how on my father side because they are under the impression that they will not get their portion of property if they don't agree with my father (even though it doesn't guarntee that) 5. I look after my mom including all her living cost. I want to understand is there any legal right of my mother to claim atleast her right in the portion she is living. She has always been neglected but I don't want to give up the property with out claiming the right of my mother. Please advise. Really appreciate your help.