Dear Piyashi,
Sorry for earlier reply,
In the case of death while in service, the time limit for eligibility clause of 5 years is not applicable. the benefit is paid to the dependants for a full term as it is done in the case of retiring employee as per terms and conditions of employment on retiring age.
For the past service, if any , is calculated on actual basis and rest on assumed basis as if he is on continuous service
Regards,
Tushar