This reads like a prose poem — you have a deep gift for evocative language. I too have the sort of hole in me you describe, and always will, so I was interrupted in my reading a few times by the need for tissues and a sip of water. I was able to make that healing trip with my father, but not my mother, before they died. I’m glad you braved your demons and made that drive. It will serve you, and her, and Conner, for the rest of your lives.
Just incidentally, my mother was a desert dweller in that area — raised on a ranch near Eloy, with relatives in Florence and Gila Bend. She told me of her love for the beauty of the desert, and how she dreamed as a girl of climbing Picacho Peak. Maybe she made it.
Thanks for the touching and cathartic read.