Dear Lannie,
This might be the listing for your mother in the 1940 census:
"United States Census, 1940," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:VRDR-D56 : accessed 31 August 2016), Fern Kipp, Tract 17, Denver, Election District T, Denver, Colorado, United States; citing enumeration district (ED) 16-231, sheet 815A, family 10, Sixteenth Census of the United States, 1940, NARA digital publication T627. Records of the Bureau of the Census, 1790 - 2007, RG 29. Washington, D.C.: National Archives and Records Administration, 2012, roll 491.
-NGP