[Ger-Poland-Volhynia] searching Mitzllaff

[Marlo50]

I think I need some help.  My husbands great-aunt was
Wilhelmine Lohroff born 1848 and married to Rheinhardt
Mitzlaff born 1847. The first trace of them is in Ohio in the 1880 census with 3 small children.  No other place until
1930 in Lindenhurst Long Island NY.  Even the spelling of Metzlaff or Metzloff does not find them in this country.
Someone tell me where to look for them?  Did they go back to Germany and I don't know where they came from.  On the 1930 census it says they came in 1873 but 
have not been able to locate them.  I am now very curious as to where did they go?   Any help in finding these people over those years?
Margaret