On other web sites I have seen the wife's name spelled as: Arzilla, Orzilla - so that may be a clue. I believe Nancy Allen, the daughter, age 17 married James Standley (Stanley) who was b. about 1833 in Indiana, They were married in Iowa.
www.google.com Stanley - Iowa Marriages 1851-1900 James Stanley married nancy Allen 8 Dec 1852 Appanoose, Iowa
The father of james Stanley was Dempsey Stanley b. 1811 in Illinois and married Clotilda. Dempsey died in 1861 age age 50 in Appanoose, Iowa. Clotilda married Adam Warford on 7 Jun 1866 Appanoose, Iowa.
James Stanley (Standley) and Nancy Allen had a son Alexander E. Standley (Stanley) b. 17 May 1855 Appanoose Co, Iowa Alexander married Cloretta (Etta) May Kellogg on Jan 1871 Monroe Co, Iowa.
These families are all connected: Mahaska County, Monroe Co, and Appanoose Co, Iowa - and the surname is sometimes spelled Stanley and sometimes Standley - makes it very confusing.
I did not find anything on Solomon Allen age 20 in the 1850 census.Part of Iowa was pioneer country when Samuel Allen went there, apparently.