Eva doesn't appear in the death certificates which go up to 1962. Missouri considers death records as private and they're not open for inspection after 1962 except for special circumstances. See http://health.mo.gov/data/vitalrecords/
for the details.
The County genealogical and historical societies seem to make up for this by compiling their own death list from obituaries and other records. The St. Louis Genealogical Society, www.stlgs.org/
has many records and they do research too. Successful Searching!