Chameli Devi was sleeping with her son Deepchand (13) in Ajnaura village of Baanpur area when her son-in-law set them ablaze last night, police said here.
While the woman succumbed to her injuries today, her son was undergoing treatment in a hospital, they said.
The accused, who has been arrested, was angry with the deceased after his daughter was married-off without his consent a day before, police added.