My sister in law demanding money

Dear sir brother committed suicide because my sister-in-law was mentally harshing him; because of it, he got very mentally depressed and committed suicide at his sasural. After his death, he left a policy, in which my mother was the nominee. he bought the policy before the marriage After we claimed it, my bhabhi began demanding half the money from his policy. I don't know what to do; please give me some advice.