It was after the Saudi foreign minister flew to Washington and had an unscheduled meeting with her husband. The White House claimed the purpose of that meeting was to discuss Syria.
Maybe she had to deliver a message from her husband that couldn’t be entrusted to anyone else who would be able to slip into the hospital without attracting attention.
That is certainly a possibility. Of course, the hospital photos suggest he was visited by any number of “homey’s” that could have been enlisted to deliver any message.
It also seems possible her visit (photos of which were intentionally made public - no one’s camera or cell phone was seized by her security team) was made available for the benefit of the muslim community...perhaps in a show of WH support.