Employer harassing mentally to leave job after serving 20+ years

My friends is working for a Trust who has a Dharmshala in Haridwar as a Manager for more then 20 years. He is living with his wife and a son from the beginning in two rooms alloted by the trust. Everything is going good and he deals all the legal disputes & financial matters as no one from trust sits there. But from few months they started harassing him and his family by making issues on senseless matters. A person from trust is doing this all who is living in Dharamshala in this period. From few days he is now allowing him to enter the office and ristrict his engagement to work as he allowed a frequent visitor to Dharamshala to park his car in premises. they are not giving anything in written line any memo or something just only saying to the peoples around that he made some financial blunders and we are firing him in asap. A accounts team came for many days to check accounts but nothing fault come. Sir please guide me to help him what can he do as he gave his precious time of his live as a devotee to them in a very less salary. Currently he is getting around 10,000 rupees and feeding his family, he has not sufficient money to fight for his loyalty. Note: 1) His all the IDs like aadhar & voter ID is in the same dharmshala address 2) His Banks accounts is clearly mentioning Manager, ..... Dharmshala. 3) Multiple Power of Atornies for handling cases is in the name of him. 4) Living & working their for more then 20+ years 5) Giving no rent ever. 6) Salary always given him in cash from Dharmshala accounts. 7) No appointment letter he has of 20+ years before. 8)But have the backup of Audited accounts mentioning his salary. 9) He come to know that he will not receive any salary from next month as he is not working. 10) Come to know that Trust is planing to sell the property.( Is this can be the reason) Please help him sir..