I see Kathryn gave you the info on the Orley Francis Boling marriage. His 11st wife, Hannah E. Reese Boling died in 1919, leaving him with 2 children, Leslie (son) & Frances (dau.) Orley/Orlie appears in the Des Moines directory through 1924.Don't find Lurana or kids in 1925 IA census.
I found Lurana Murphy in Des Moines, Polk, IA in 1915.She is shown as Merina Murphy 28, widowed, occupation housekeeper, with 2 children Francis age 2 (shown as female) and Lurenna E. 2mos.They are living at 682 25th Street.
Since they were married in 1908, not living together in 1910 and he's dead or gone by 1915, censuses won't help.
Since both Earl Francis Boling and Lurana E. Hoetger show Murphy as father's name on the CA death index, you should probably get their applications for SS numbers.They should show parents names and may yield more information on the mystery "Murphy."
Lurana's sister, Vera, was married in Des Moines in 1914 to Lou D. Mcclintic, so Des Moines may be a place to focus on.
Given the apparent movement of "Martin Murphy" (MN, SD, IA) he may have worked for a railroad.