Found nothing on Wade's death, but this might lead to a clue...
I found this 1880 census record which appears to be for the family.
"United States Census, 1880," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:M4P9-DVR : accessed 11 June 2016), A Cuningham, Beat 4, Prentiss, Mississippi, United States; citing enumeration district ED 173, sheet 244D, NARA microfilm publication T9 (Washington D.C.: National Archives and Records Administration, n.d.), roll 0663; FHL microfilm 1,254,663.
Wade's older brother William is listed and his younger siblings are listed, but Wade at age 11/12 is not. Was he with relatives? Or working on a local farm as a laborer? Are the older children together?
There is also a J. P. Cunningham right next door with wife Sarah. This might be John Pinar. The birth year seems to align.