Rights of daughter

Dear Sir/Madam, I am married woman and presently living in Ranchi, Jharkhand. I have one unmarried younger brother who's age is 32 years. My father passed away on 13th may 2019. Age of my mother is 52 years. My father was a government employee and my mother is getting pension benefits. My father has a flat in kolkata where my mother and brother is living presently. My Father was not done any testament against property before his death. The flat of Kolkata is still in the name of my Father. Till date I have not claimed anything as my brother is not working and income anything. But from few days I am notice that my brother is misuse my father's left out property and I have decided to safe the property. I want to claim my rights but as still my mother is alive I am feeling guilty to demand. I want to claim my rights after my mother's life. Is it possible? If I want to claim now then what is my rights? How the flat will be divide? Can I claim the rights from my present address which is in other state? Thanks with regards