The incident happened last night in Chatol village where Deepchand and his family where hit with stones and sticks by Deepchand's sister's husband Bhairo Lal and his associates, they said.
Deepchand died on spot while his grandson Raju received critical injuries and is being treated at the district hospital, police said.
Bhairo Lal wanted a share in Deepchand's ancestral land, which was denied by the latter, police said.
"Four persons have been detained in the matter and others are being searched," police said.