He was Jesse Delmar Keath, son of Joseph Keath of Illinois and Kate of Michigan & Irish parents. Jesse was born in Kansas, probably in Chanute in Neosho Co., was a railroad conductor. He married Nellie Seery, dau. of William & Matilda Seery, about 1909-1910. As you know, he served in WWI. He survived the war & returned to Chanute and can be seen there in the 1920 census, with the in-laws living with him and the wife.
Still married as of 1930, there is no sign of children in the household.
He lad a brother Lester who probably left offspring, there are some KEITHs in the SSDI for Chanute.
The real mystery is figuring out why your mom had the photo! Possibly, he was stationed in Texas durring the war. Did you mother live anywhere near an Army fort?