I didn't find their deaths in the WV Early Vital Records, www.wvculture.org/
. Death records weren't required during that time period.
Nicholas County records are on microfilm at the Virginia State Library, www.wvculture.org/history/archives/
. they have wills 1820-1969. You might find them in those records.
You can contact the Nicholas County Historical & Genealogical Society, www.facebook.com/
and ask if they have indexed death notices or cemetery inventories.
Also there is a web site for Nicholas County Historical Society Cemetery Project, http://nicholaswv.org/
that might have info about where they were buried. Successful Searching!