When I found what appeared to be the marriage of Margaret's daughter Rosina Hoffman in 1872 (see Rosina married John Eiler) I looked for the couple in the 1880 census. I found a John "Iler" with wife Rosa. He was born in Hessia Darm[stadt] and she was born in Switzerland. He was a farmer and they were listed with two sons, Frederick and George. The location was Clear Creek Township in Keokuk County, Iowa.1 They were in eastern Iowa not very far from the Illinois locations of other Hoffman family members. Here is the census page (remember to click on the image to see it larger) with a detail of the "Iler" family. Note that the census taker spelled John's name as it sounded just like the Stephenson County Clerk in the marriage record. It should be written as Eiler. I'll continue with the census records in the next post on Rosina.
1. 1880 U.S. census, Keokuk County, Iowa, population schedule, Clear Creek Township, Enumeration District (ED) 159, sheet 185D, dwelling/family 61, John Iler household, digital image, Ancestry.com (http://www.ancestry.com : accessed 11 March 2009), citing National Archives microfilm publication T9, roll 349.