Question: What is the date of death of Herbert Masaryk's mother?
Sentence (from "Herbert Masaryk"): Herbert Masaryk (1 May 1880, Vienna – 15 March 1915, Prague) was a Czech Post-Impressionist painter; son of the future founder and President of Czechoslovakia, Tomáš Masaryk, and his American-born wife, Charlotte Garrigue.
Relevant evidence: Yes