Question: Who most recently served as Chief of Staff to the wife of the 47th Vice President of the United States?

full_context: Document 1: Lynne Cheney: Lynne Ann Cheney (née Vincent; born August 14, 1941) is an American author, scholar, and former talk-show host. She is the wife of the 46th Vice President of the United States, Dick Cheney and served as the Second Lady of the United States from 2001 to 2009.
Document 2: Kirstjen Nielsen: Kirstjen M. Nielsen is a government official and national security expert who currently serves as Principal Deputy White House Chief of Staff to U.S. President Donald Trump since September 6, 2017. She informally performed the role of Deputy Chief of Staff since the time John F. Kelly became White House Chief of Staff on July 31, 2017. Nielsen had previously served as Kelly's Chief of Staff at the Department of Homeland Security. She is the founder and former President of Sunesis Consulting. Prior to serving in the Trump administration, she was a senior fellow and member of the Resilience Task Force of the Center for Cyber & Homeland Security think tank at the George Washington University and served on the Global Risks Report Advisory Board of the World Economic Forum. She holds degrees from the Georgetown School of Foreign Service and the University of Virginia Law School.
Document 3: Electoral history of Joe Biden: Electoral history of Joe Biden, 47th Vice President of the United States (2009–2017), United States Senator from Delaware (1973–2009). To date Joe Biden has not lost an election.
Document 4: Joe Biden: Joseph Robinette "Joe" Biden Jr. ( ; born November 20, 1942) is an American politician who was the 47th Vice President of the United States from 2009 to 2017. A member of the Democratic Party, he represented Delaware as a United States Senator from 1973 until becoming Vice President in 2009.
Document 5: Marilyn Quayle: Marilyn Tucker Quayle (born July 29, 1949) is an American lawyer and novelist. She is the wife of the 44th Vice President of the United States, Dan Quayle, and served as Second Lady of the United States from 1989 until 1993.
Document 6: Jill Biden: Jill Tracy Biden (née Jacobs , previously Stevenson; born June 3, 1951) is an American educator who is married to the 47th Vice President of the United States, Joe Biden. She was the Second Lady of the United States from 2009 to 2017.
Document 7: Huma Abedin: Huma Mahmood Abedin (born July 28, 1976) is an American political staffer who was vice chair of Hillary Clinton's 2016 campaign for President of the United States. Prior to that, Abedin was deputy chief of staff to Clinton, who was U.S. Secretary of State, from 2009 to 2013. She was also the traveling chief of staff and former assistant for Clinton during Clinton's campaign for the Democratic nomination in the 2008 presidential election.
Document 8: Hunter Biden: Robert Hunter Biden (born February 4, 1970) is the second son of former U.S. Vice President Joe Biden and his first wife, Neilia Biden. He is a partner at Rosemont Seneca Partners, LLC and is Counsel to Boies, Schiller, Flexner, LLP, a New York-based-law firm.
Document 9: Kellyanne Conway: Kellyanne Elizabeth Conway (née Fitzpatrick; born January 20, 1967) is the current Counselor to U.S. president Donald Trump. She is the first woman to ever run a successful presidential campaign. She has been a Republican Party campaign manager, strategist, and pollster, and was formerly president and CEO of The Polling Company Inc./Woman Trend.
Document 10: Hillary Clinton: Hillary Diane Rodham Clinton ( ; born October 26, 1947) is an American politician who was the First Lady of the United States from 1993 to 2001, U.S. Senator from New York from 2001 to 2009, 67th United States Secretary of State from 2009 to 2013, and the Democratic Party's nominee for President of the United States in the 2016 election.
Document 11: Kristie Canegallo: Kristie Canegallo was the Deputy White House Chief of Staff for Implementation for U.S. President Barack Obama. Her responsibilities included the execution of major projects such as health care reform, education, and the war in Afghanistan.
Document 12: Political positions of Joe Biden: Joe Biden served as the Vice President of the United States from 2009 to 2017. He served in the Senate from 1973 until 2009 and made his second run for President of the United States in the 2008 presidential election as a Democrat. Biden was announced as Democratic presidential nominee Barack Obama's running mate on August 23, 2008, and was elected Vice President on November 4, 2008.
Document 13: Mike Donilon: Mike Donilon, a lawyer and political campaign consultant, is a partner at AKPD Message and Media. Between 2009 and 2013, he served as Counselor to the Vice President under Vice President Joe Biden. Prior to his White House appointment, Donilon worked with the vice-presidential candidate to help him prepare for the debates and also as a traveling advisor. He has been an advisor and consultant to Vice President Biden since 1981.
Document 14: Office of the Vice President of the United States: The Office of the Vice President includes personnel who directly support or advise the Vice President of the United States. The Office is headed by the Chief of Staff to the Vice President of the United States, currently Nick Ayers. The Office also provides staffing and support to the Second Lady of the United States. It is primarily housed in the Eisenhower Executive Office Building, with offices for the Vice President also in the West Wing, the U.S. Capitol and in the Vice President's official residence.
Document 15: Sheila Nix: Sheila Nix is an American political strategist, most recently serving as Chief of Staff to Jill Biden, the wife of Vice President Joe Biden since April, 2013.
ground_truth: Sheila Nix