Dear Shri Mohla Ji,
The nomination executed by the deceased member is binding on the EPFO. Final payment of EPF account is to be made to the nominated mother only. Please ensure that you furnish a copy of the nomination accepted by the competent authority with the claim. If the EPFO official is still adamant, meet the superior officer and submit the claim. You may also insist for a written reply from the official who is refusing to accept your claim papers. Please do this and then revert.
Father is eligible for EPS, 1995 pension. He has to file separate application in form 10-D quoting the name of mother in the family member's details column. After the death of father, mother will receive pension.
Thanks and regards,