Henrietta was buried in St Mary's churchyard, Hexham (about 5 minutes from where I live) on 24th May 1894, abode 'Convent of Hexham'.
I have looked again at the image closely in light of what information has come forth and although not 100% about this I think I can now make sense of a few more words of the inscription. I think it might read ..
..'ISABELLA THOMPSON
HIS WIFE WHO DIED AT ABERDEEN
AUG 27 ..'
I don't know what any one else might think .. is the part about Aberdeen there or am I imagining it? Might she have gone back to Aberdeen after Jarrow where you, Millmoor have discovered her, I wonder? When I next get time to get to that cemetery I am going to have another close look at the inscription.
You are quite right about Aberdeen and the date!
Isabella senior died aged 81 on 27th August 1873 at Nazareth House, Cuparston, Aberdeen.
She is described as the widow of John Thompson, merchant in Shields, her parents Peter Mellis (deceased) and Elizabeth Mellis, maiden surname Strichen (deceased).
Despite her husband's name being wrong, this has to be the correct person I think.