DeMuth was born as Marie Ann Dresden in Mineral Point, Wisconsin, as the eldest of eight children born to William and Catherine (Schill) Dresden. As a young adult, she was employed as a milliner in Milwaukee.
In 1926, DeMuth married her first husband, Carl H. King. They had one son, Carl Jr.
DeMuth was widowed in 1961. Three years later, she remarried to Vincent D. DeMuth. The marriage lasted 11 years before she was widowed a second time. Her lifelong hobby was collecting dolls.
DeMuth was preceded in death by her husbands, her parents, five of her siblings, and her grandson Paul King. Her maternal family had a history of longevity, with her mother dying in 1985 aged 104, and her grandfather living to the age of 88.
DeMuth died in Fort Worth, Texas, on 6 June 2011 at the age of 110 years, 213 days. She was survived by her son, two grandchildren, two great-grandchildren, and two of her brothers, William and Urban.
DeMuth’s age was verified by Jimmy Lindberg and Stefan Maglov, and was validated by LongeviQuest on 7 May 2024.