The deceased was identified as Laxmi Devi and her son Abhishek was injured and rushed to a local hospital.
An FIR has been lodged against the accused Ram Gopal Thakur, his elder brother Arjun and two others in connection with the murder, SSP Nitin Tewari said.
According to the police, Abhishek had eloped with Rinki, the daughter of Ram Gopal Thakur, on March 6, 2013 and the couple got married on December 11 last.
"In the preliminary investigation, the allegation of deceased family appears to be correct. However, stern action would be taken after investigation against those found guilty," Tewari said, adding no arrests have been made so far.
According to the FIR, Ram Gopal, Arjun and two started indiscriminate firing after barging into the house of Abhishek, in which Laxmi was shot and she died on the spot.