Hello Tabitha,
Have searched for Isacc Griffiths in Hope under Dinmore, Allensmore and Wellington but drawn a blank I'm afraid. So I did a search on the 1851 name index and came up with only one likely candidate who is living in Canon Pyon :-
1851 - Derndale, Canon Pyon
Isacc Griffiths 13 Serv Unm General Servant Herefordshire, Burghill
Also ran a check on 1961 for Canon Pyon, but no luck, he must have moved on by then

I did , however, come up with this lot who I think (because I've read your other posting) are his parents -
1861 - Westhope Hill, Canon Pyon
Richard Griffiths 56 Head Mar Ag. lab Hereford, Dewchurch
Sarah Griffiths 42 Wife Mar Hereford, Howmer Deaf
Daniel '' 18 Son Un '' Alinsmore
Alin '' 15 Son Un '' ''
Tabitha '' 10 Daur Un '' Burfil (Burghill?)
Eliza '' 7 Daur Un '' ''
Joshua '' 1 Son '' Canon Pyon
Hope this helps
Sue