Found her on the 1870 Naples, Ontario, New York census (img 53) as Mary Coons
Found her on the 1880 South Bristol, Ontario, New York census (dist 137 img 17) as Mary B. Coons
Mary Coons, daughter of Wm. and Cynthia Coons, died Aug. 11, at 3 o'clock A. M. Although her death had been expected for some time, yet none were prepared for the sad announcement. She was the light and sunshine of the household, at once lovely and beautiful. Her early death is rendered more sad from the fact of her intended marriage with La May Brand, who fully realizes his great loss. The bereaved family have the sympathy of the entire community.
The funeral services were held at the house, and conducted by Elder Woodruff, who delivered a touching discourse from the first epistle of John, 3rd chapter, 1st verse: "Behold what manner of love the Father hath bestowed upon us, that we should be called the sons of God." The remains were deposited in Rose Ridge, whither they were followed by a large concourse of relatives and friends. - Naples Record August 19, 1881