Robert, they are both buried in the Bartley Cemetery, Bartley, Red Willow County, Nebraska.
Hoppe, August D. 9-28-18284/5/1910
1910 McCook Republican Grandpa Hoppe, the aged father of J.W., died Tuesday evening of this week at the home of the latter in this city at the advanced age of 87 years.Funeral services will be conducted at the M.E. church this afternoon at one o’clock and interment made in the Bartley cemetery.Bartley Inter-OceanFriday 15 Apr 1910
you can find a picture of their stone plus Baby Erma Ruth on www.findagrave.com