Liability of heirs in deceased person's amount recovery.

I need a help from lawyer community for an recovery notice that has been sent to us.

My father was a director member in Co-operative society. In 2005 one of the director misused the funds and  fraud case was slapped against all the directors and commitee members of the said co-operative society.

In 2011, My father died while the case was still going on. Now recovery officer sent notice to us by Registered AD few months back but postman didn't give it to us as my father was deceased and it was meant for him. Yesterday

recovery officer from district recovery department came in and gave us notice personally for recovery to my mother and took acknowledgment on it.

I need advice on following questions.

1 My father got deceased in 2011. Recovey notice is being sent in 2014. Can such a notice be sent to  deceased person or his heirs.

2 What is the liability of the heirs. Do we need to pay the amount that has been asked in the recovery.

3 How do we prevent Recovery department taking action against us.