Kate L. Mitchell - Texas

Looking for information on Kate L. Mitchell/Mitchel of Karnes County, Texas. She shows up in the Texas census for 1860, 1870, and 1880 as a widow, born in TN abt 1836. I don't know if Mitchell/Mitchel is her maiden name or married name, but there are several children with the same last name. The two oldest children were born in TN in the late 1850's and the others in Texas in the 1860's.

I can't find her in the 1900 census, so I assume she died between 1880 and 1900, most likely in Karnes County, DeWitt County, or Gonzales County.