Mou legal standing

Facts : My father entered into an MOU with a builder to sell the land - the land was under letigation when the MOU was done - terms were to buy the land as it is - so we negotiated the price at a lower rate - deal was supposed to be closed in 1 month - against the MOU the buyer forwarded a cheaque with a repict of 5 lakh - but later he did not completed the deal and waited for 3 years due to court letigation on the mentioned property - stared giving reason as matter is in court and all - so we cleared the property and asked for some rise in consideration as the property was not purchased in the said condition on the day of MOU it was clear property now.- He refused to do so - and so we returned his cheaque along with paper notice and all - to cancel his MOU - he refused to take the cheaque and claims his right on property ,- we have not given any rights to him - MOU was done on 100 rs stamp paper on which my father has not signed - the only catch is he did not mention any expiration date of MOU , what standing does the buyer has here , does he gets any rights.