No enquiry proceedings could be conducted after the retirement of an employee. Anyway, what is the age of retirement as per the terms of your appointment letter? If you have already crossed the age of retirement, the company management can never insist you to continue your job any longer. The company should have completed the enquiry proceeding before the date of your retirement, or they should have extended your service period. In my opinion, you are at liberty to refuse to participate in enquiry proceedings.
In the present matter, since you have already crossed the date of retirement, the company cannot insist you to continue your job any longer. Similarly, you are not bound by the outcome of the so-called inquiry proceeding; you may refuse to participate.
As for PF dues, you may contact the Provident Commissioner, sign an affidavit stating that you have retired as per the terms of your appointment, and demand settlement of your PF dues from PF authorities. As per the Supreme Court ruling, nobody can withhold your dues. The PF is not attachable as per the provisions of the CIVIL PROCEDURE CODE (SEC 60).