I agree with jwp - it's a 14-fret 1929-33 OM-45 with torch inlay (custom feature at extra cost). Along with the pre-war D-45 and 1959 Les Paul sunburst, it's a Holy Grail of collectable guitars. I'll bet an open C chord never sounded so musical.

Benton's son Thomas Piacenza, known generally as "T. P.", went on to a long career as a flautist.

I'm no good at guessing babies' ages from photos, but if the little girl is about two, then the photo is probably 1941. Benton's son was born in 1926 and his daughter in 1939.

I'm fairly certain it's a Martin. The girl's hand makes it hard to count the number of frets clear of the body, but it looks like it may be 14 and the flatness of the top of the upper bout seems consistent with that. That would make it either a 1929-33 "OM" or a post-1933 "000" (the OM and 000 are the same size and shape, and I think it looks too big to be a 00). The fancy inlay headstock indicates a style 45 (higher numbers means fancier decoration and usually better wood). I believe it's a 1929-33 OM-45 as I believe starting in 1934 "C. F. Martin" always appears on the headstock, though I could be wrong about that, especially for the fancier models.

A 1930s OM-45 or 000-45 would run roughly $50K to $100K today, depending on condition and how badly a collector wanted it; the price is really whatever the traffic will bear. In the 1930s, the catalog prices were $180 and $170, respectively ($3K to $4K today).

It that guitar is what I think it is, you could retire on the selling price of it today. What a nice photo!