http://archive.org/stream/HistoryOfSult ... 0/mode/2up
OK, Samatar. Here's the source of the photo. See especially the last four pages and the references on the last page.
I am fairly certain the paragraph that begins, "South of the main cave-well is the considerable tomb of Abdullah Hasan senior" describes the tombs at Falaad, in which case they are not similar to those pictured. The ones at Falaad are like covered bowls on pedestals or columns, maybe 15-18 feet high. They have narrow vertical wooden doors just in the bowl part.
Wiki is generally up-to-date and a good place to start. Often, information is available nowhere else. In this case, we don't end up with any more names. It's Hassan's mother and father, Sultan Nuur, a Habr Jeclo and two unknown Hawiyes.
Wouldn't mind seeing Xplaya myself.