My two cents. If price is ok for you, I would recommend pre-clearance in Dublin.
You haven't said how old your mother is, or if she's in great health, but going on the fact you're 30 I would assume she's probably in her 60's. The immigration arrivals hall at JFK has to be one of the worst places in the Western hemisphere. Any option you have to avoid it would be beneficial to the traveller, particularly one of age, who may not like standing in a hot, humid, cramped room with hundreds of other passengers all equally frustrated at how long it's taken to get your passport stamped.
(I apologise in advance if my presumptions are incorrect. I mean no offence to anyone)