Many thanks for your query to Ireland Reaching Out.
The name Hillgrove appears to be listed under the Catholic parish records of Cahirciveen and those records are accessible on the Irish Genealogy website at www.irishgenealogy.ie They are under the Church Records tab. Unfortunately, though it appears that those records don't start until the mid-1840s. The parish register is available to view through the National Library of Ireland under this link:
http://registers.nli.ie/parishes/0658. However, the records are very difficult to read.
Have you considered writing directly to the Parish Office in Cahirciveen? As you have particular dates, names and a place, it is possible that they may have more information for you.
There is a Cahirciveen parish website which may be of some assistance to you:
http://www.cahersiveenparish.com/church-records-from-1825-onwards. You will note that there were earlier records but the register was destroyed by fire.
If you have further questions, please don't hesitate to contact us.