I think crushed stones would be nice and maybe you can incorporate it somewhere else in your yard so you have a nice uniformed look.

I would think you could find some drought tolerant plants that would grow in that small space that would help soften all the hardscape. Anything from a low ground cover in a variety of green colors to an ivy or morning glory climber to a taller low profile plant like kangaroo paws

Cedar chips is another idea and you can get them in black.

I think rocks are an excellent choice. I would look for rocks that are close to the same color as the driveway since the driveway does not have a clean edge, this will camouflage the raw driveway edge nicely.