Hi Shauna, I checked Washington State Archives, Ancestry and Wenatchee Area Genealogical Society but didn't find anything on Willard, Susan or Matthew.
Birth and death certificates weren't required in Washington until 1907 and marriage records weren't required until 1968 on a state level.
However, some counties were keeping track of these records before 1907.
You can contact the Douglas County Clerk, 509-745,8529 and the Douglas County Auditor, 509-745-8527 to see if they have any death records as early as you need.
You can contact the Washington Public Library, sos.wa.gov/library/obituaries.aspx to see if they have an obit for Willard from the Douglas County Empire Press.
Susan and Matthew might have moved to B. C. since there isn't any additional info about them in Washington Digital Archives. When you contact the Clerk and Auditor's office, ask them if they have marriage records for the time period they were married. Successful Searching!