sale of property

for illeterate people the thumb impression is required. NOwadays more frauds are coming up, so rules have been changed now. Every one has to put thumb impressions/eyes scan along with their signatures on the documents. 

Now-a-days both signature and thumb impression are necessary.  If an illetrate, only thumb impression.

yes now a days all by bio matric registration therefore both is must 

Hello, Greetings of the day!
For the query you posted, I would suggest that:
Everyone has to put thumb impressions along with their signatures on the documents. For illiterate, a thumb impression is required. 
Usually, biometric registration is used nowadays.
Hope it helps
Regards,
Sneha Jaiswal