Insurance, beneficiary

I need help or insight about this matter. My grandfather recently died. He’s a retired US military, dual citizen US and in the Philippines. But, he lived in the Philippines through out his life. He have both family in the US and here in the Philippines.
My Dad is the only legal son under his name but my Dad died before him. Is there any insurance, benefits or something that we can claim? If yes, what are the documents needed or action to take?