The victim, identified as Shrikant, was reported critical till late last night. He was declared dead this morning, DCP (South West) R A Sanjeev said.
The incident was reported between 2 PM and 2.30 PM yesterday. According to preliminary investigations, the police said, the victim's 28-year-old mother allegedly tried to kill him and his 10-month-old brother, before hanging herself from a ceiling fan at her residence.
All three of them were rushed to Deen Dayal Upadhyay Hospital, where the woman was declared dead.
The incident was reported when neighbours heard the children crying uncontrollably, and one of them later went to check on the family. Her husband, who is a plumber, was called up. He rushed home and, meanwhile, neighbours also called up the police control room and reported the matter.
The woman and her husband are both natives of Odisha. They got married in 2006 and later moved to Delhi. Their eldest son, who is eight-year-old, lives with his grandparents at their native village in Odisha, the official said.