The site irishnative.com has pics of the Granlahan graveyard.
This one is labeled "Dempsey Family Cloonreliagh":
We're hoping to get our woman on the scene (well, kinda sorta nearby) to get us a better picture. Hopefully we can make out more details. The close up of the photos are blurred.
http://irishnative.com/cemeteries-2/granlahan/#bwg50/18192
This one is labeled "Martin Grady Grange". Great-grandfather Thomas had an older brother Martin (born 1848). It is *possible* this is him.
http://irishnative.com/cemeteries-2/granlahan/#bwg50/18100
6/9/2022 update:
Note that the Kiltullagh parish lists two graveyards in Granlahan. I'm not sure where the second one is, but this one is directly St Patrick's Church, just after the junction with the L1602 road:
Based on a tip from Kath I looked for Thomas Harte in the Ballintober graveyard. He is there, along with Bridget O'Grady Harte:
https://www.findagrave.com/memorial/120277924/thomas-harte
https://images.findagrave.com/photos/2013/316/120277924_138439685128.jpg
Looks like: "Thomas Harte. Died Dec 29, 1937. Age 53 years. His Wife Bridget. Died Aug 18, 1975"