Hello, Jui,
I have checked both the piece nos you give for the 1881 census for the Bevan name. The first one,RG11/5244 folio 95 page 11, that you say is your couple shows just Henry age 58 & Martha age 58. The second one, RG11/5422 folio 96 page 11 is not a couple but sister & brother in law.
I did find a Margaret Jane Bevan, if you follow the census info, you might be able to tie them in together.
1881 census
RG11/5422 folio 96 page 11
3rd Row 4 Row Bedwelty, Tredegar, Sirhowy
Martha Bevan Wid age 52 Housekeeper b Ebbw Vale
Martha dau unm age 20 Lab in Brickworks b ditto
Henry son unm age 16 Haulier in Coal Mine b Sirhowy
Walter son age 13 Haulier in Coal Yard b ditto
Kezia dau age 8 b ditto
William Bevan brother in law unm. age 52 Coalminer b Radnor.
1871 census
RG10/5323 folio 44 page 16
99, no 4 Row Bedwelty Tredegar, Sirhowy
Henry bevan age 50 Iron miner b Radnor
Martha wife age 50 b Mon. Bedwelty
L(S)emual son unm age 26 Haulier b Brecon Dukes Tours
Benjamin son age 16 Collier b Bedwelty
James son age Iron Miner b ditto
Kezia dau age 13 b ditto
Martha dau age 11 b ditto
Henry son age 9 b ditto
Walter son age 4 b ditto
William son age 2 b ditto
Margaret Matthews Mother W. age 85 b Brecon, Brecon
1851 census
HO107/2418 folio 812 page 3
150 Five Rows Bedwelty Tredegar
Thomas Bevan age 28 Miner b Radnorsh.
Martha wife age 24 b Monmouth
S(L)amuel son age 4 b Brecknock
MARGARET JANE dau age 2 b ditto
William Bevan Relative unm 24 Miner b Radnorsh.
Hope this is not too confusing & is of some help.
Meliora