There are several Eliza(beth) Powell's in Monmouth Reg in the correct time period - I can't be sure of which one :-)

Elizabeth Powell 1860 Apr-May-Jun Gloucestershire, Herefordshire, Monmouthshire

Elizabeth Rose Powell 1860 Oct-Nov-Dec Gloucestershire, Herefordshire, Monmouthshire
Elizabeth Jane Powell 1861 Jul-Aug-Sep Gloucestershire, Herefordshire, Monmouthshire
Eliza Ann Powell 1862 Apr-May-Jun Gloucestershire, Herefordshire, Monmouthshire
Elizabeth Powell 1862 Jul-Aug-Sep Gloucestershire, Herefordshire, Monmouthshire
Elizabeth Powell 1862 Oct-Nov-Dec Gloucestershire, Herefordshire, Monmouthshire
Eliza Powell 1863 Apr-May-Jun Gloucestershire, Herefordshire, Monmouthshire
Elizabeth Powell 1863 Jan-Feb-Mar Gloucestershire, Herefordshire, Monmouthshire