Depriving from Property

Sir, Iam the only son of my parents (no other son or daughter). My father had received a gift of 50% of property from his grand mother and balance 50% was given to my aunt. The entire property was handed over to the builder. The building was demolished and a new construction came up. As per agreement with the builder my father got two flats (1950 sq ft and 1000 sq ft) and cash. Similar arrangement was with my aunt. My parents stay in the bigger flat and I with my family occupy the smaller flat. The property is in Kolkata. Due to my transfer in service, I am posted outside Bengal. My parents (father) is repeatedly asking me to vacate the flat which has my belongings locked in. The relationship has deteriorated and they are not in touch with me and does not want to meet me or my family. Meanwhile my father has gifted the properties to my mother. They are even planning to sell the bigger flat without informing me. Kindly advise what to do as my wife and daughter's future is in stake (a) Can my father gift the property to my mother without any information to me or my consent? (b) Can my mother sell this property (my father is still alive) without informing me? (c) Can I raise an injunction on the property on the grounds that I am being deprived? (d) Can I claim 50% of the property as this is totally ancestrally obtained and my father has not self acquired through his means.