trsnscription errors are common enough say one in every family would be my guess
I rechecked the hospital for first names H or E with last name M and H without success.
1911http://www.census.nationalarchives.ie/pages/1911/Antrim/White_Abbey/White_Abbey/190643/ .
my searches threw up McMeekins in the area, could Henriette b 1880 have stayed with one of them so heres my search
1901 CENSUS
1 in Drains (Cairncastle, Antrim)
http://www.census.nationalarchives.ie/pages/1901/Antrim/Cairncastle/Drains/994560/Mc Meekin Agness 30 Female Daughter Non Sub Presbyterian
Mc Meekin James 77 Male Head of Family Non Sub Presbyterian
7 in Drains (Cairncastle, Antrim)
http://www.census.nationalarchives.ie/pages/1901/Antrim/Cairncastle/Drains/994565/Mc Meekin Isabella 17 Female Daughter Presbyterian Co Antrim Seamstress Read and write - Married -
Mc Meekin William 57 Male Head of Family Presbyterian Co Antrim Farmer Cannot read - Married -
Mc Meekin Isabella 60 Female Wife Presbyterian Co Antrim - Read and write - Married -
1911 C ensus
http://www.census.nationalarchives.ieNo 1 in Drains now Loughrirdge family
No 7 in Drains now Doull, McNeill, Wilkinson,
No 10 in Drains now the McAllisters
No 14 in Drains
14 in Drains (Carncastle, Antrim)
http://www.census.nationalarchives.ie/pages/1911/Antrim/Carncastle/Drains/194637/McMeekin William 67 Male Head of Family Presbyterian Co Antrim Farmer Read and write - Married
McMeekin Isabella 70 Female Wife Presbyterian Co Antrim - Read and write - Married - 28 1 1
McMeekin Isabella 27 Female Daughter Presbyterian Co Antrim - Read and write - - - - - -
31 in Drains (Carncastle, Antrim)
Mc Meekin Agnes 48 Female Head of Family Unitarian Co Antrim Farmer Read and write - Single -
Buchanan Mary 28 Female Visitor Unitarian Co Antrim - Read and write - Single - - - -
so no sign of HENRIETTA HAMILTON B 1880 staying in 1911
Agnes McMeekin could be her cousin?
Henrietta Hamilton died in Drains not Drain Bog the PRONI valuation revision after 1911 I will check out more carefully next
Henrietta Moore might have been buried from the Abbey hospital to Carnmoney graveyard [more than cemetery]