The woman's brother filed a police complaint alleging that her husband was behind the incident as she was raising objection over his illicit relationship with his sister-in-law.
Pratima Singh and her son Saksham (4) and daughter Swetcha (3) were killed when their house caught fire in Pure Ishwarnath village under City Kotwali police station area late last night, incharge of police station Balram Misra said.
A case has been registered against deceased woman's husband and sister-in-law and two others in this connection, police said.