I agree with Shirl, the family are at Guilsfield in 1891, despite the inconsistancies.
If you look in 1901, your great grandfather Richard is at Peniarth, Meifod:
Richard Griffiths (26), Waggoner
Margaret Jane " (24) His wife
Frederick " (under 1m) son
Frederick " (13) Brother
This brother Frederick (13) ties in with the Frederick (3) in 1891 in Guilsfield.
Also, in 1901, Richard Griffiths, senior seems to have moved to Shropshire :
Living at Cottage, Stanton upon Hineheath, Wem, Shrops.
Richard Griffiths (50) Ag. Lab., b. Meifod
Mary Ann " (19) Dau
John " (11) Son
Susannah " (

Dau
Ellen Jane " (6) Dau
George B. " (1) Son b. Guilsfield
This last child being born in Guilsfield also gives you further proof of the 1891 census.
However, Richard (senior) in 1901 is still shown as married, though wife Susannah is not at home.
Further investigation suggests she was at The Salop Infirmary at the time:
Susannah Griffiths (46) though shown as b. Welshpool, Dolanog is not far away.
I have your greatgrandfather Richard (aged 36) at Penyfoel, Meifod in the 1911 census, with wife Margaret (34) & 5 children. (Frederick (10) Herbert (9) Susannah (6) Edward (4) and Florence (2))
Good luck
Stan