Mary N. Jackson married Thomas F. Applegate in 1871 Upper Freehold. He was the executor of William's estate, and the land was sold in 1889, deed signed by Ellen Jackson's mark, Mary N. Applegate & Thomas F. Applegate. It states Mary was his only child (meaning living, a son had died previously) and Thomas was her husband.
Ellen Jackson is living with Mary & Thomas in 1900 in Extonville near or in Hamilton, Mercer Co. Thomas was a farmer. He was murdered on his farm in 1901 by Samuel Shinn, who worked for him and went to prison for it.
Mary died in Trenton in 1909 at the home of her daughter & son-in-law, Hannah & George E. Tams. Mary & Thomas Applegate were buried at Cream Ridge cemetery. If Ellen died before Mary, I'm sure she's buried at Cream Ridge but there's no headstone as far as I know.
George died in Belmar in 1926 and is buried at Greenwood cemetery in Trenton. I don't know yet when Hannah died but it was after George & maybe between 1930-1940. She seems to be in Neptune Township in 1930 census. They had a son named Theodore who married Ruth, possible maiden name Berry.
No news about Ellen. I was in Trenton this week but couldn't find a death certificate or obit between 1900-1910. There is an Ellen Jackson who died in 1915 in Asbury Park but that is not the right one.