Do you know the names of her children? In 1992 there was a MargarOT living in Auburn WA. I also found listings for other Fiedelak's.
This is the only death record I found;
Washington Death Index, 1940-1996 about Rudolf A Fiedelak Name: Rudolf A Fiedelak Date of Death: 2 Dec 1992 Place of Death: Pierce Age: 55 Estimated Birth Year: abt 1937 RESIDENCE: Auburn Gender: Male SSN: 304-42-7489 Certificate: 033942