As far as I know, there's no Ruby Marshall in any of the families I'm researching. I did find a Ruby Marshall living in San Antonio, TX. She's counted in the census with her parents, Joseph and Frances Scruggs, 1910-1930. Joseph could be a son of Solomon and Fanny Scruggs, counted in 1880 census in Gonzales, TX. If this is not your Ruby, you might try a first name only search for all African-American (black, mulatto, etc.) females named Ruby who were born in Louisiana circa 1908.

1880 census: District 71, Gonzales, TX
Head--Scruggs, Solomon, 25, preacher, b. LA, parents b. MS
Wife--Fanny, 18, keeping house, b. TX, parents b. NC & SC
Son--Joe, 7
Son--Charles, 6
Son--Jerry, 2

1910 census: 1112 Castro Street, San Antonio, Bexar, TX
Head--Scruggs, Joseph, 39, 2nd marriage, butcher at packing house, b. TX, parents b. TX
Wife--Frances, 29, 1st marriage, laundress at home, b. TX, parents b. TX
Dau--Ruby, 2
Dau--Lenora, 2
Roomer--Washington, Henry, 49, single, street laborer, b. VA, parents b. VA

1920 census: 1416 Albert Street, San Antonio, Bexar, TX
Head--Scruggs, Joe, 53, truck driver at freight company, b. TX, parents b. US
Wife--Frances, 40, no occupation, b. TX, parents b. US & GA
Dau--Lenora, 12
Dau--Ruby, 11
Son--James, 8

1930 census: 333 Lambrano Street, San Antonio, Bexar, TX
Head--Scruggs, Joe, 35, married at age 17, laborer at odd jobs, b. TX, parents b. TX
Wife--Frances, 35, married at age 17, no occupation, b. TX, parents b. GA
Son--James, 18, married at age 16, laborer at odd jobs, b. TX
Dau-in-law--Della, 16, married at age 14, no occupation, b. TX
Grandson--Franke (Frank), 3 months
Dau--Marshall, Ruby, 22, married at age 20, cook in boarding house