Question: What is the date of death of Padmanabhan Nair's wife?
Sentence (from "Padmanabhan Nair"): A son of the Kathakali guru Pattikkamthodi Ravunni Menon, Padmanabhan Nair was one of the early-batch students in Kerala Kalamandalam, where he subsequently joined as a teacher and retired as its principal in 1990.
Relevant evidence: No