If you can help in solving this, please email Jan Main.
I have received information from Evelyn Sass regarding the identity of Cecelia. This information doesn't tell us which Nathaniel Nye she married, but lets us know who she is. It is believed she is Rosanna Cecelia Barris, the daughter of Isaac R. Barris. Please note that I have made changes to her name. Since her marker has put the 'R' in the position to be a middle name, I have put Rosanna as her middle name.
This is what Evelyn shared with us: "ROSANNA CECELIA BARRIS, born abt. 1836 in Beaver Co., PA; died prob. 1858. Rosanna appears to have been the only child of Isaac R. Barris [Orphan's Court records for Beaver Co., PA, Vol. 1&2, p. 254, dated 8 June 1842.] Court records do not list her mother's name; however, on the 1850 Beaver Co. PA census for Franklin Twp., p. 170, family #5, we find Cecelia Barris age 14, b. PA living in the household of Samuel Hazen and wife Elizabeth. Marriage records for Beaver Co., PA provide a marriage date for Samuel (Hazen) and Elizabeth Barris in Oct. 1849. So 14-year-old Cecilia apparently now went by her middle name and was living with her mother and step-father. The cemetery records for the Providence Baptist Church cemetery in North Sewickley Twp. has a grave recorded for Cecilia R. Nye, wife of Nathaniel Nye. A birth date is not given, but a death date of 24 Aug. 1858, age 21 is given. This would mean a birth date of c. 1836-37 which would correspond to the Cecilia Barris in the 1850 census. Cecilia is buried near Enoch W. Barris who would have been her uncle and near Nancy Barris who would have been her grandmother. It is believed that this Cecilia Nye was Rosanna Cecilia Barris."
Thanks Evelyn for this information!!