Final answer:
The question regarding when Grace Dobson was named chairwoman of the Board cannot be answered with the information provided, as there is no mention of an individual by that name in the context of serving as chair of a Board of Governors or any board.
Step-by-step explanation:
The information provided does not include a date or event where someone named Grace Dobson was named chairwoman of a Board. The details given list former and current Chairs of the Board of Governors, such as Alan Greenspan, Ben Bernanke, Janet Yellen, and the current Chair, Jerome Powell. Additionally, some information is provided about an individual named Grace Morris Craig, who had a memoir about World War I. However, there is no mention of a 'Grace Dobson' and no data regarding the date she was named chairwoman of the Board.
Therefore, without additional context or information, it is not possible to provide an answer about when Grace Dobson was officially named chairwoman of the Board.