There is not much available in online subscriptions for New Jersey. Resources are relatively good before 1920 and for the last 15 years or so.

If they died in New Jersey, the Jersey City or Newark libraries may be able to help.

If the obituary was in the NY Times, the archive is online, with a purchase option of $3.95 for a single obituary. NYTimes obituaries are free before 1923 and after 1986. http://www.nytimes.com/ref/membercenter/nytarchive.html

Good luck!