The incident took place last night at Fandpuri village and the main accused has been nabbed, they said.
The son, Amit Singh, claimed that his mother Pushpa had illicit relationship with someone. This prompted him to kill her, Saharanpur SSP Nitin Tiwari said.
Amit's father, Rajeev Singh, claimed that incident happened due to some family disputes, police said.
Rajeev has registered a complaint with the police.
The body has been sent for postmortem and police are further probing the matter, police said.