Property rights

Great Grand Father purchased agricultural land in 1920. he died interstate in year 1950. he left one son (your grand father) and 1 daugher ( your grand aunt). Revenue records were only there in the name of your grandfather. Now you want to know that your grand aunt children can take claim or not ?- Since death occured on 1950 and Hindu succession act does not apply retrospectively, so it is important to apply the pre hindu succession act . Under Mitakshara law before 1956, if male hindu died interstate leaving one son and one daughter, the sone took the estate in preference and daughters rights were much more weaker, unless there was no male heir. So as per the mitakshara law, your grandfather becomes the full legal heir and grand aunt sone will not get anything . they will only get the share  whateever your grand aunt has. 

But agricultural land, many states has adopted their own special tenancy/land revenue laws.  Khata/Pahni does not estingish title by itself. So even your grand father name alone was entered, grand aunt may still file, partition suit, declaration suit, challenge to old mutation, under local tenancy law, if they show under 1950 law, she had a share subject to law of limitation