Can wife claim husband's property after his death?

My cousin sister's husband committed suicide a year ago, Her in-laws harassed her physically & mentally. as a result she forced to leave her in-laws house. Now her in-laws decided to sell all their property & will give all their property & money to their daughter. My sister has a 4 year old son... They also said that ...she herself and her son have no right in their property...can anyone tell me is there any provision or law which help my sister? Are they have any rights in their in laws property?