Sister in law asking share in property of mine and father's

sir i am from mysore my elder bro expired in the month of november 2015, my father has divided the property he earned to both of us equally which is registered in the taluk office, my late brother has two male children one is 08yrs old who is mentally abnormal & another one is 02yrs old they are staying with us only in my house which is in the name of me & my mother, my brother has sold everything father had given to him. now his wife is creating a lot of problem in my house she is asking share in the house which is constructed by me & my father, my brother did not invested a single paisa.