Your post seems to suggest that you already have the 1900 Census for
Sallie. So I've skipped that and gone on to the 1910 Census. I don't
have access to it, but you might also see if anyone could do a
lookup in 1885 LA State Census, or the 1895 AR State Census.
1910 Census Magnolia, Columbia Co., AR
Martin Thomas Head M B 58 married 9 yrs 2nd marriage b. AR Father
USA Mother GA Occu: Farmer
Sallie Thomas Wife F B 58 married 9 yrs 2nd marriage 20 children
born 13 still living b. GA Father GA Mother GA
Fred Thomas Son M B 16 single b. AR Father AR Mother AR
J. K. Thomas Grandson M B 12 single b. AR Father AR Mother AR
1920 Census Magnolia, Columbia Co., AR
Martin Thomas Head M B 65 married b. AR Father USA Mother USA Occu: Farmer General Farm
Isabell Thomas Wife F B 70 married b. GA Father USA Mother USA
So Sallie died between 1910 & 1920, probably in Magnolia, Columbia Co., AR. Her date of death can be narrowed down a bit further to between 1910 & 1913, as her name isn't recorded in the AR Death Index, which begins in 1914.