Was "your" Frank in the US Marines Aug 9th 1945 to Aug 27 1946? Because the Frank Riendel that is in the SSDI with death Oct 18, 1982 was (card issued in SD). A family tree online at Ancestry has this Frank's spouse as Nora Gilbert, but spelling Reindel for surname. SSDI, Marine Muster Rolls and VA BURILS file has Riendel.
Nora Reindel has residence in IA in 1993 and may still be living but could also have remarried.