I didn't find Clark. I assume he died before the 1900 Census. I'd contact the Topeka Genealogical Society, www.tgstopeka.org/cpage.php?pt=8
and ask if they have any early death info, obituaries or cemetery inventories.
I did find the following about Elizabeth Belle while looking for Clark.
Res: Fort Worth, TX, 1909
Spouse: Charles Burnside
Source: Fort Worth, Texas City Directory 1909
1910 Tarrant Co. TX
Newt Mcnay, b. PA, 45, widower, farmer
Lizzie Burnside, b. KS, 24, widow [incorrect], 3/3 ch, cook @ home
Johnny, b. TX, 9
Mary, b. TX, 7
Maud, b. TX, 7
Am Daves, b. IL, 66, boarder, widower
Charles had re-married before 1910.
1910 Fort Worth, Tarrant, TX
Maggie Larason, b. MO, 36, div, 3/3 ch, dressmaker @ home
Robert Lee, b. TX, 12
Pauline, b. TX, 10
Charlie Martin, sonlaw, b. TX, 23, trucker
Jessie, dau, b. TX, 19, 0/0 ch
Frankie Martin, adopted, b. TX, 1 11/12ths
Charles Burnside, b. CO, 33, boarder/lodger, M2, laborer
Louise, boarder/lodg, b. MO, 30, 4/0 ch
Lucretia Currie, b. NY, 59, boarder
Donna Lee, adopted, b. AZ, 19
1920 Tarrant Co. TX
Mack G. Allman, b. TX, 60, laborer working out
Bell, b. KS, 35
Andrew Burnside, stepson , b. TX, 19, laborer working out
1930 Tarrant Co.
Mac L. Allmon, b. TX, 60, laborer general
Elizabeth, b. KS, 48
1940 Tarrant Co.
M. L. Allman, b. TX, 70, education=4th grade
Elizabeth, b. KS, 56, educ-8th grade
Born: 2 March 1882, Topeka, KS
Father: C. W. Cowan
Res: Fort Worth, Tarrant, TX
Informant: Mary Kinchen [daughter]
Died: 22 Nov 1966, All Saints Hospital, Fort Worth, Tarrant, TX
Buried: Rose Hill Burial Park, Ft. Worth, Nov 28, 1966
Source: TX Death Certificates 1903-1982
I'd look for her obituary to see if her parents are mentioned in it. Successful Searching!