Willis J Riddick - date of death.

National Archives and Records Administration (NARA); Washington, D.C.; Non-population Census Schedules for North Carolina, 1850-1880: Mortality and Manufacturing; Archive Collection: M1805; Archive Roll Number: 1; Census Year: 1849; Census Place: Gates, North Carolina; Page: 257

This lists death in early June, at the beginning of register, year ending 1850, ie 1849-1850. The June 5 noted by John may be correct, although I can not find the exact date.