Hi Eunice, The 1930 Census is the most recent one available to the public at this time. (The 1940 Census will be available to the public in 2012 but who knows how long it will take to index it.) Therefore, it is more difficult to find family records after 1930 at this time.
Also Idaho is restrictive about releaseing death information until 50 years after the person's death "although certificates ' may be issued to any applicant who can show direct and tangible interest in the record' at an earlier date." [Go to http://www.idahohistory.net/documents/guidetovitalrecords.dochttp://www.idahohistory.net/documents/guidetovitalrecords.doc .)
They do seem to be willing to search for death dates and obituaries for a fee.
I also looked through the Social Security Death Index and a Marie Merrill born 18 Dec 1911 died March 1973 but death location not specified. Her social sec. # was assigned in NJ. See http://ssdi.rootsweb.ancestry.com/cgi-bin/ssdi.cgihttp://ssdi.rootsweb.ancestry.com/cgi-bin/ssdi.cgi . Hopefully you'll have more info about her birth date and will be able to decide if she is YOUR Marie or not. Successful Searching!