Gratuity, PF & Full and Final settlement

I'm writing on behalf of the family of a deceased colleague of mine. He expired 5 years back in office during his duty hours due to natural cause. He had got married only 2 months before his death and was survived by his wife, mother and a physically challenged younger brother. The father left the family decades ago and there is no contact with him. Within a week of his death the wife went back to her parents home and got remarried approx. 2 years back. The family is not aware of the wife's whereabouts now. The family (mother & brother) were solely dependent on the deceased for their livelihood and have no other source of income. The organization asked for a heirship certificate from the district court which they submitted but now they are asking for a succession certificate to process any claims. Please advise what is the way forward in this case, the wife is one of the beneficiaries legally but has remarried and not in contact, the father also is separated (not formally) from the family with no contact. Is there any remedy for this family to claim the benefits?