The old stand by is reload a previous save. Just to be sure, you saw the beds correct? there is a side wing, they may be sleeping. There is also a courtyard out back that comes into play in a bit, make sure they are not out there. Best of luck
There has been issues with NPC's not showing up in correct areas sometimes way off the map and not being able to get to them.
The quest the OP mentioned was one of the first ones that had this issue.
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I believe the Beta patch for the PC has this issue fixed. No idea when it will be live on the Consoles.