Regarding lic policy

Dear Sir/Madam, Greetings of the day, I am Bhupesh residing in Rohtak Haryana. My younger Brother Dinesh Kumar met with an accident and got expired, he was a government empolyee as a clerk in BEO office for last 5 years. He was having a LIC Policy of worth rs. 5,00,000/- in which I was standing as a Nominee. Now the claim has become rival because his wife has also taken stay from the court and LIC has asked her a Succession Certificate. Willingly, I was ready to give the claim amount to the son (3 Years Old) of deceased as soon as it was coming in my account. But due to non trust on me she took this step. After her this step, Now I want that all amount should be in the name of my brother's son rather than his wife. being as a nominee in the policy what rights I have? what if she will be able to bring the succession certificate from the court? can i also go for the succession certificate? presently legal heirs as per class who are alive Class 1 son of deceased, wife of deceased, one expected child (going to born soon) Class 2 father of deceased, brother and sister of deceased