Frank is listed on the 1900 census but not on the 1910. The youngest child on the 1910 is Lizzie, age 7, so I assume that Frank died between 1907 and 1910.

Selina is listed as Celina and her maiden name was Rogers. Found marriage record for Frank and Selina for March 14, 1889, St. Mary's.

Their son Ernest was listed at 8 years old in 1900 but is not listed on the 1910 census. The last son, William, was 8 years old in 1910.

Found Irving (head of house) along with siblings Viola, Mary, and William on the 1920 census for Los Angeles, California.

Not sure if this is your Frank Jr., but

Found a Frank Stafford on the 1930 census (b. 1900, in Louisiana) for Oakland, Alameda County, Ca. He was an inmate at the city prison. His occupation was auto mechanic.

Cannot find Frank Sr. listed on the Death Index for the State of LA.