It has recently been discovered through pages on WK Holmes in History of Texas published during his lifetime that his mother-in-law was the sister of Rev. Jesse Tubbs. In researching this line, it was discovered that the Rev. was the son of George William Tubb Sr. and Catherine "Polly" Brunts. Mary was his daughter by his previous wife Jean McNees.
Info from Janelle Holmes

They had 13 children:
Catherine Martha Blasingame 1825 – 1881
Mary Blasingame 1826 – 1880
George W. Blasingame 1828 – 1866
Jane Caroline Blasingame 1829 – 1911
Calvin Blasingame 1831 – 1856
Thomas Blasingame 1834 –
Luther Blasingame 1835 –
Frances J. "Fannie" Blasingame 1837 – 1928
Henry Blasingame 1837 – 1857
Sarah Blasingame 1839 – 1880
William Woodson b. 1842
Columbus Blasingame 1845 – 1934
Nancy Blasingame 1849 –

Estate of Mrs. Mary Blassingame, Dec'd
40 bus corn " WK Holmes for 40.00
1 yoke steers " RB King " 30.00
100 lbs bacon " BM Whittin 9 3/4 c 68.25
1 Bell " RB King 3.00
5 steers " Thos. Lindsey 10$ each 50.00
18 head of cattle to WK Holmes 2.50 each 45.00
Mark & brand " " 8.00
1' lot Hogs to GK Cesna for 40.00
12 head " WK Holmes 30.00
4 Bee-gums " R SMith 4.00
1 Filly " CC Blassingame 65.00
1 Waggon " Ben Tubb 22.50
1 Lot Plows " R Smith for 9.87
1 Plow " Mr. Topett 1.50
1 Lot reins? " R Smith 8.00
1 Lot Bells " Pat Smith 5.50
Bell & Saw " RB King .78
1 Lot Casings " Jack Cash 7.50
1 Tubb " A Goodwin .60
2 Chairs " R Smith 5.25
Sundries " WK Holmes 15.25
1 Stack Fodder to Jas Brown 9.75
$477.97

From Find a Grave Contributor Janelle Holmes
Mary Blasingame is most likely buried on the family farm in Leon County, Texas, near what was called Clapps Creek, as is her son George W. who died about the same time. Court records which include loose notes and bills, indicate the Dr. last visited her on the 11th, twice, and there are no further visits, so she probably died that day.