The 109A bus from the airport passes by Lismullin.
From Dublin City Centre:
The 109 bus passes by Lismullin
The 109B bus does NOT pass by Lismullin
The 109X from Busarus, City Centre exits the motorway at Garlow Cross which is near Lismullin. If you take this bus, then get off at Garlow Cross stop and by arrangement telephone Lismullin to be picked up.