I think these are the family you are looking for. Not in Llanddeiniolen Parish church but in Macpella noncomformist cem.
Pencefn (1883);
WILLIAMS, John, 25.11.1883, 81
WILLIAMS, Jane, gwraig, 3.04.1892, 82
Llanffinan, Sir Fôn (1917);
ROWLANDS, Jane, merch, 24.12.1917, 86
gwraig = wife
merch = daughter