Ananthakrishnan said he and his mother was travelling on a narrow road near Anchal when Ganesh Kumar's car came from the opposite side.
"I stopped the car and since there was more space for Mr Kumar's car to go a little back, so both the cars could pass through, we thought he would reverse his car. But he, instead of doing that, came out and hit me and showered abuses on my mother," he alleged.
The woman said the legislator not only used bad words against her but made her a vulgar gesture and beat her son.
Ananthakrishnan and his mother have sought medical treatment at a nearby hospital.
The lone legislator of Kerala Congress-B since the 2016 assembly polls, he is now supporting the ruling Left Democratic Front, despite being a member of the Congress-led United Democratic Front between 2011-16.
A minister in the Oommen Chandy government, he had quit the cabinet after a quarrel with his wife, whom he had subsequently divorced.