It is useful to have the exact birth date to find a person on the web. In the case of Ellen Nilan, she was born in Ballinderreen to Thomas "Nilan" and Sally? King on 6 March 1867. The Family History Library number for this birth is 101143. This information may be accessed on Ancestry.com with a free two week subscription. There was an Ellen "Neilan" who sailed out of Londonderry bound for New York on the Anchor Line passanger ship Devonia on 20 March 1891. The voyage was listed as 32 days in length. Her age was registered on the ship's log as 24, which is consistant with a birth year of 1867. Her occupation was listed as "None". She sailed with a Bridget (age 19) and James Nilan (age 9). All three were listed as "single". This would be important if she became an American citizen, because the naturalization papers are stored by the US Government by arrival date.
There was another Ellen "Nelan" who arrived in New York on the Germanic on 19 April 1886. The ports of departure were Liverpool and Queenstown. Her age was listed as 19 which would have meant a birth date of approximately 1867. The counties were listed on the manfest, but her's was unreadable except for "Ireland".
There are no civil registrations of Marrage for her registered in Gort that I could find on Ancestry.com or any other site, although there was one for an Ellen Nilan in Loughrea in 1888. There were several Australian, England, andUS marriages that would be consistant with her age and date of birth, but there were no parents listed.
I could not find any death records that listed parents names.
Good luck in your search,
Pat Vail
Albuquerque, New Mexico, USA (Husband of Ann Fahy of Coolfin, Ardrahan, Co Galway)