Additional District and Sessions Judge, Hisar, Raj Kumar Yadav sentenced the brothers, Inder Singh and Amit, for murdering Shakuntla and her daughter Anu, prosecution said.
The mother-daughter duo was admitted to a private hospital with serious burn injuries on May 5, 2010 and the infant died after a few hours.
Shakuntla in a statement before a Duty Magistrate alleged that she was sleeping with her daughter when someone poured kerosene and set them on fire.
In a complaint to the police, father of the woman alleged that her daughter was burnt to death by her in laws.
A case was registered by the police under relevant provisions of the law against the woman's husband Inder Singh and his brother Amit.
During the probe it came to the light that Singh took the extreme step due to strained relations with his wife.