Generally, his family can contact his former employer, with sufficient proofs of their relationship. The employer can provide his last known address, as well as any information as to wages due, financial instruments held in his name, i.e. life insurance policies, investment vehicles, stock, and the like. If he had "direct deposit" of his wages, the employer may have the name of the financial institution holding his funds.
However, in this day of internet fraud/ scams, the probability of receiving any information from the employer without clear and compelling evidence that the persons presenting themselves as "family" (parents, brothers, sisters) are who they claim to be is nil.
I would recommend that the family contact the Indian embassy/ consulate closest to his last known address and invite them to solicit the services of a US attorney who can investigate the matter and represent the family's interests.
If there is no Will, and no record of immediate family, depending on the State where he lived, his assets could be claimed by that State after a reasonable period of time.
Regards,
PALADIN
