Rani Bai and her grandson Chatu (5) were asleep when the roof of their rented house collapsed, killing them instantly, Kotwali police station inspector M M Sharma said.
He said that Rani's son, who was out of station, had taken the house on rent from one advocate Babulal Yadav.
The police inspector said that the house was in bad shape and unworthy of living.
A case has been registered a case and it is being investigated, he said.