Seventy-seven-year-old Narayan Devi died due to hanging like the other 10 members of the Burari family, according to her post-mortem report.
The bodies of 10 members of the family were found hanging from an iron mesh attached to the ceiling on July 1, while that of Narayan Devi was found lying on the floor in another room of the house.
The Delhi Police have received the post-mortem report, a senior police officer said.
A belt was found near Narayan Devi's body, the officer said.
The report has ruled out any foul play and said that she died due to "ante-mortem" hanging, he added.
Police had already received the post-mortem reports of the other 10 members.
The post-mortem reports of the 10 other members of the Chundawant family said they died due to hanging and no external injury marks were found on the bodies except for a few scratches, the officer had said yesterday.
"The final opinion states that the family members died due to ante-mortem hanging," he added.
Narayan Devi's daughter Pratibha (57) and two sons -- Bhavnesh (50) and Lalit (45) -- were among the deceased.
Bhavnesh's wife Savita (48) and their three children -- Neetu (25), Maneka (23) and Dhirendra (15) -- were also found dead.
The others found dead were Lalit's wife Tina (42), their 15-year-old son Dushyant and Pratibha's daughter Priyanka, who got engaged last month and was supposed to get married by the year-end.
The police had also found 11 diaries, which contained "psychological musings" and certain things written about the "road to god".