Facing difficulties in settlement of PF & EPS

Hello Sir, My father was working with a small private company for long time & he quit his job in the year 1999. He had resigned the company by giving a written resignation. The employer was not accepting his resignation at that time, but my father had left that organization; He had also not joined any other establishment further; He had no other support documents (joining letter / relieving letter / Salary slips) of his employment with that company except the PF Slips. My father had tried earlier to do a final settlement/Withdrawal of PF & submitted his application for withdrawal of PF, but his application was returned back to the PF office with out signed by the employer; The employer refused to sign those docs. My father got passed away 4 months before in the age of above 58 yrs. Hence recently, i put forward an email with my queries to the online grievance management Systems portal of EPF India. And i got an response from them as “You are advised to submit the claim in form No.20, form No.10D(if death in service if the member completed more than 10 year membership) otherwise, apply in form No.10C for withdrawal benefit under EPS, 95 in respect of the legal heirs entitled U/P 70 of EPF Scheme, 1952 along with the copies of death certificate, legal heirship certificate, birth certificate of children below 25 years of age, 3 nos. of passport size photographs, SBI A/c no. of any one out of six Banks mentioned in form No.10D duly countersigned by his father’s employer for settlement of PF & EPS dues.” Could you please advice me, if the employer is not willing to sign on the desired documents for the settlement of PF & EPS dues as he did earlier; is there any further alternatives/possibilities for settlement of PF & EPS dues in our case. Is it possible to get back the PF amount without the permission/notice to the previous employer which my father used to work. My mother is alive and by default she would be the nominee to claim for settlement of PF & EPS dues; is it required to apply for legal heirship certificate also? Shall we require to present any affidavit before PF Commissioner for not claiming the PF Dues since long time? Please advice me, if any further documents required. Looking forward your suggestions for the same. Thanks, Bijay