Time line to settle FFS when company has informed to resign?

Let me understand about time line to settle FFS when company has informed to resign and considered 1 month notice period for working and after this all charge is handovered but they had hold the ffs to finalise the accounts which is not possible within that time line.
Over all 2 months salary is on hold not clearing

Talk to them verbally as well as in written to Find the exact cause why it is not done in time

This is harassment which few companies indulge in. They don't understand that the existing employees are watching. Normally F&F should be cleared within 30 days of last date of employee working.
You have not mentioned designation without which correct way forward can't be shown.

Dear Friend,
From your inputs, it is clear that applicable notice period was of 1 month.
This is for your information that Employer holds salary for said notice period for security purpose.
Holding 2 months salary is not good idea . It should be one month that is for days you served during your notice period.
First refer your relieving policy of the company for more insights. If discrepancies exists, better bring down on written communication with ex- employer.
Regards,
Sapana

Thanks for your suggestions, Surprise is that they had not issued any one Appointment order nor confirmation letter. Only we have proof that salary get deposited into account that suffix the employee. Being AGM Finance as per profession handovered the things but while settlement they are saying to finalise the books as I got relived on April end and I need to close books of previous year. This cannot be done even discussed that at time of relive whatever task is there that should be taken care by new comers, simple cannot hold it as max organisation freeze the books during July - Aug. Need to understand how to convince them if not agree than what next ...legal action will be the last remedy but it impact on Carrier.