When Makeni Ecumenical Centre acquired a farm in Mwembeshi for their agricultural settlement project back in the late 70s or early 80s (I guess) the plot had an old farm house on it and some graves of the original occupants, named Nel. I am not sure if these graves are visible any more, not having been there myself in 20 years or more. However, I have found this photo, which shows two of the grave stones.
The one in the foreground seems to be Danielena J. Nel Feb 1925 - 9 March? 1929?
The other appears to have been scratched, sadly... It looks like it begins "Dina". I think I have another photo elsewhere, though probably no better.