The police said on Sunday morning the family members found Kasiammal dead.
During the preliminary inquiry, they found Kasiammal and Namakodi were having a dispute in recent days as the woman refused to give money for him to buy alcohol.
In this circumstance, the police believed the mother-and-son duo had a heated argument in the night hours before he assaulted her to death.
Usilampatti taluk police shifted her body for post mortem to government hospital.
The police added that the couple, Kasiammal and Paulsamy, have three children including the suspect Namakodi. Namakodi has been living with Kasiammal after he separated from his wife due to difference of opinion. Since then, Namakodi has become an alcoholic.
The police registered a murder case against Namakodi and launched an investigation.