My grandmother purchased land on 1965 from ex serviceman

At 1965 my grandmother purchased land from ex serviceman, who was alloted 10 acres from Madhya Pradesh government. after 50 years, son of that person sued us, with following points 1) under Madhya Pradesh land revenue code 1959, section 168,7-b which is [ (7-b) Notwithstanding anything contained in sub-section (1), 4[a per son who holds land f rom the State Government or a person who holds land in bhumiswami r ights under sub-section (3) of Section 158] or whom r ight to occupy land i s granted by the State'Government or the Collector as a Government lessee and who subsequently becomes bhumi swami of such land, shall not transfer such land without the permission of a Revenue Off icer , not below the rank of a Collector , given for reasons to be recorded in wr iting 2) on the registry papers, the person(from which we bought land) stated in writing that "i am buying land at different location, that is why selling 10 acre plot", in front of registrar. 3)in MPLRC 1959,section 168,7-b was injected on 1980, with MP land revenue code ammendment act 1980,that permission of collector is required, but our land transaction was completed at 1965. a) i want to know that is there any risk for our land? b) i am not getting any information on MP land revenue code ammendment act 1980, on Madhya pradesh land revenue code, there is footnote that at 1980, sec 168,7-b was injected, i want to verify this can i do that.