Can i buy a gramakantam land in adibatla, hyderabad.

It is not necessary that the gramakantam property should belong to government 

It can be a personal property also.

You may first obtain a proper legal opinion from an experienced lawyer in the local and proceed only if recommended.

Being a non-Tamilian I had to search for the meaning and purpose of "gramakantam land" (a local terminology) as the term used by you, accordingly I found, 

"Gramakantam lands," in the context of Andhra Pradesh and Telangana, refer to government-owned lands, traditionally open spaces in villages, managed by the local village panchayat, where villagers could utilize the land with permission but without acquiring ownership rights.  

In such circumstances the land can neither be sold nor purchased since title of the land shall not be transferred and it will remain with Panchayat.

Any gift / sale deed executed, as stated by you, is invalid and illegal.

However, it is advisable to contact and consult a local prudent lawyer for appreciation of facts / documents and professional advise. 

In villages it has become a practice for the villagers to acquire the open  or vacant housing lands,  they are ocupying them as owners and the village authorities also do not object to the occupation of the local villagers, but of course the occupiers cannot claim title to the occupied property.  But as they know the tricks to convert such lands as ancestral properties and create revenue records on their names, they become their own property.

That is how many such properties become their own properties.

However it is not advisable to purchase the property without a proper legal opinion from any experienced local lawyer