I found the following maybe it will help.
THOMAS, M L MRS (1920 U.S. Census)
NORTH DAKOTA , MCKENZIE, WHATFORD VILLAGE; RUD
Age: 56, Female, Race: WHITE, Born: MN
Series: T625 Roll: 1335 Page: 260
granddaughter Stella Mae Haley age 10 born ND
(Stella living with grandmother)
Stella was probably orphaned and living with her mother's widowed mother. Couldn't find anything of Stella's parents.