The accused, Pandurang Sindu Aagde, residing in the district's Goregaon area, had differences with his son Channa Aagde (36) over the sale of wheat, they said.
Following an altercation with his son over the same issue Pandurang attacked him with a hammer, killing him on the spot, police said.
He also attacked his wife Birenbai Aagde (57) and daughter-in-law Yogeshwari Channa Aagde (32) when they tried to rescue Channa, they said.
A police team rushed to the spot and admitted the two critically injured women in Gondia's KTS hospital, where they succumbed during treatment, they said.