In the 1880 census of Newport, there's a William J. Carroll, a 26-year old stone mason, and his wife Elizabeth (age 24) lodging with a woman named Bridget Garrick. Both William was said to be born in Rhode Island; Elizabeth in New York. Their parents are all from Ireland.
They don't show up in any other searches in the Rhode Island area after that. Is it possible he moved out of the state?