I know of only one house in Carnfishin in the townland of Ballyhemlin and about one mile south-east of Bushmills. Its modern address is 30 Haw Road.
You can find the location of the townland at Placenamesni.org and the location of the house at Land and Property Services, Northern Ireland.
Click Geographic Information and Mapping tab on left panel
Click GeoHub NI link and register to use - it's free
Select envelope icon (2nd from top right) and type in 30 Haw Road - the Carnfishin location
Click on 30 Haw Road, Ballyhemlin and you're there