I have (sort of) a source for their marriage: LDS Vital Records Index, Birth & Marriage Index for New Hampshire, FHL #1000968: Jefferson Franklin Barney & Mary Ann Young md. 25 Sep 1847 in Grafton, Grafton Co., N.H.
Mary Ann (Young) Barney is in a couple of censuses that I have found, living with her daughter Ella (Barney) Smith:
1905 State Census, Cedarville P.O., Valley Township, Smith Co., Kans., p.10 (37?), #54.
A. S. Smith (male), age 54, b. Vt., Farmer, to Kansas from Illinois
E. E. Smith (female), age 49, Ill., Housekeeper, to Kansas from Illinois
A. W. Smith (male), age 24, Farmer
H. C. Smith (male), age 19, Farmer
M. M. Smith (female), age 17
J. A. Smith (male), age 15
W. E. Smith (male), age 7
M. A. Barney (female), age 79, b. Maine, Housekeeper, to Kansas from Illinois.
1910 United States Census, Valley Township, Smith Co., Kans., ED 203, Sheet 7A, #132/132.
"Smith, Aaron S., head, age 57, md. 37 years, b. Vt., parents b. Vt., Farmer - General Farm
Smith, Ella E., wife, age 54, md. 37 years, 8 children, 7 living, b. Ill., Fa.b.N.H., Mo.b.Maine
Smith, Herald C., son, age 24, single, b. Kans., Fa.b.Vt., Mo.b.Ill., Farmer - Home Farm
Smith, Jesse A., son, age 20, single, b. Kans., Fa.b.Vt., Mo.b.Ill.
Smith, Winfield E., son, age 12, b. Kans., Fa.b.Vt., Mo.b.Ill.
Scott, Mary A., daughter, age 22, widow, md. 3 years, 1 child, 1 living, b. Kans., Fa.b.Vt., Mo.b.Ill.
Scott, Lorenzo E., grandson, age 1, b. Kans., parents b. Kans.
Barney, Mary A., mother-in-law, age 84, widow, md. 60 years, 4 children, 2 living, b. Maine, parents b. Unk.