The civil parish for that Glebe townland is Mayglass, and it's part of the RC parish of Ballymore. Baptism records for this parish go back to 1813, and marriages to 1802, and are available on microfilm Pos. 4246 in the National Library.
Have you birth records for any of the children, or a marriage cert for Richard and Alice ?
Searching forward in time for Maria is more difficult than searching backwards, as none of the usual clues apply - she could have died before the start of civil records, or moved away from the area. Difficult to search for her in civil records among all the other Maria/Mary [O']Grady, unless you have some clues to narrow the search. Have you found your [O']Grady family on the 1901 return ?
Update : The townland of Ballycappoge is in the Civil Parish of Mulrankin, which is to the west of Ballymore parish. The RC parish for this area is Kilmore. There seems to be quite a few gaps in the records for this parish, but they go back to the 1750s.
Shane