Ruebhausen was born as Lillian Giese in Leavenworth, Kansas on 2 July 1905. With five brothers and one sister, she was one of seven children born to Albert and Mary (Hunner) Giese. All five brothers predeceased her, while her sister Arlene outlived her.
Ruebhausen married her husband, Ewald, on 19 September 1924 aged 19. The couple had two sons, Dean and Robert. She worked as a homemaker and was a member of various local organisations and societies.
Ruebhausen died on 2 April 2016 in Edwardsville, Illinois at the age of 110 years, 275 days. She was survived by her son Robert, as well as three of her four grandchildren, six great-grandchildren, and three great-great-grandchildren.
Ruebhausen’s age was verified by Stefan Maglov and Jimmy Lindberg, and was validated by LongeviQuest on 17 May 2024.