Nolan, Nolun

We are traveling to Ireland for the first time with my father-in-law. He has a great-grandfather (James Nolan) who came to the US from Ireland.  He has found on his gravesite New Ross, Wexford and is in search of gravesites for James Nolan's parents.  Paddy and Betty Nolan.  We are kind of stuck......Any help would be greatly appreciated!