Hi Acts Says the below Points,
Nomination (Sec 6)
Each employee who has completed one year of service is required to make a nomination
for the purposes of gratuity in case of his death. There can be more than one nominee.
(Form F).
Nominees may be changed at any time by the employee, by giving a written notice to the
employer. (Form H).
If no nomination has been made, it shall be paid to the legal heirs of the deceased
employee or if the heirs are minor, the share of such minor shall be deposited by the
controlling authority with a bank till he attains majority.
if no nomination is named , you may ask nominee to prove they are legal heirs of the deceased person. By providing certificate like family ration card, marriage invitation etc.