The first Catholic parish established in Hempstead was Our Lady of Loretto in 1871. At 104 Greenwich Street, Hempstead NY 11550, its telephone number is 516-489-3675. This location is about a half-mile south of the center of the village, with Main Street becoming Greenwich Street.
The parish website is linked here. On it, I notice that the associate pastor is a Jesuit, Felipe Rufes Vasquez. In the foyer, a bulletin board would suggest that the parish is (as announced by the diocese of Rockville Centre in 2013) under the direction of the Idente Missionaries.