Your posting doesn't say what information you already have.I found them in the 1930 census
1930 North Tarrytown, Westchester County Michale Hyland40Ire Molly42Ire Berdie20Ire Maurice19Ire David 17Ire Anna13Ire Mary7NY
I found a Social Security death index for Maurice Maurice F. Hylandb. 2 Aug 1910d. June 1991 SSI # 093-01-8632 Tarrytown.
There were a number of SSI records for David Hylands and I'm not sure which, if any, might have been him.
There is also a family tree on Ancestry.com.The owner, Seanb58, may have a connection to Mary because there is a husband listed: Albert Downing born 1924 died 1998.Since he was a WW2 vet, there is a record of his burial in Sleepy Hollow Cemetery540 N. Broadway, Sleepy Hollow, Tarrytown, NY 10591. Mary's dates are Oct 23, 1922 to Feb 17, 2007.It shows that they had three children but no names given (just designated as living.)
I sent a message to Seanb58 telling him about your Genforum posting.
You might also want to post on the Westchester County forum.