illegal claim of a lady as 2nd wife to diseased father, rights of son

I am the only son of my late parents. My father did not work for more than 30years as my mother died in accident i was 8 yrs old. my mother was a Government employee. now recently my father died. now some lady claiming herself as second wife sending legal notices to claim movable and immovable properties of my mother and maternal grand mother and all the death benefits from transport and her department, insurances, site etc of my mother who was a Government employee maintained by my father. he received family pension till his death. She herself is a rich spinster no children having two house, Government pension, agricultural lands etc. I just want to claim legal rights. Still if she goes cruel can I claim her property as she is childless and has fabricated documents as second wife to my father. please advice.