Jobi John, former Students Federation of India's Idukki district president died, and his mother was seriously injured when mounds of earth and rocks fell on their home following heavy rains at Vazhavara early on Wednesday, police said.
However, his father escaped unhurt and informed neighbours who engaged in rescue operation.
The mother's condition is stated to be serious and she has been taken to a hospital in Kochi for expert treatment.
Thiruvananthapuram district authorities are taking precautionary steps like restricting flow of tourists to hill stations like Ponmudi in view of heavy rains.
People are also being advised to avoid travelling during night on hilly roads.