If that is the right one on WorldConnect, he is in the 1880 census in Post Oak, Johnson Co., MO:
Thomas J. Caldwell, age 47, b. KY, parents b. KY
Martha S., age 41, b. VA, parents b. VA
Lulu M (or H), age 23, b. MO, school teacher
John J., age 19, b. MO, laborer
Ida B., age 13, b. MO
Rosseau L., son, age 9, b. MO
Editha L., age 6, b. MO
Myrtle, age 3, b. MO
In the same location is a probable for Martha's father, Benjamin Holmes, age 76, b. VA.
Thomas J. and Martha are buried in the Sunset Hill Cemetery, Warrensburg, Johnson Co., MO - you can find them on findagrave.com.Thomas served in the Civil War.