The accused, Karan Dev Chopra (30), had been pressuring his grandmother Surjit Sarna for a greater share in property but when his demands were not met, he allegedly assaulted her, police said.
The elderly woman has suffered grievous injuries on her forehead, eyes, knees and other body parts and is currently undergoing treatment at Max Hospital, they added.
In her complaint, she alleged that he "banged her head" on the wall and tried to strangulated her to death while shouting that he will kill her, police said.
The elderly woman also claimed that Karan's wife also didn't stop him when he was assaulting her, they added. Karan had been allegedly asking her to oust her paternal grandchildren from the property and write it in his name, police said.
The woman's paternal grandchildren stay on two floors of the house while Karan and his wife stay with Surjit on one floor of the Greater Kailash house, they added.
Karan got married in January this year and wanted one more floor for himself and his wife, said a senior police officer.
Surjit didn't budge and he used to threaten her. A case has been registered and the accused has been arrested.
Karan is the son of Surjit Sarna's daughter, who stays in Dehradun and is divorced.