By drugging their tea of course. It'd be easy, as she's the one who prepares it. No fuss, no muss. They're sleeping like babes and she's in and out with no one the wiser.
The easiest way is obviously just to walk right past them, since they will all be shocked and awed by his mere presence and giddy that he even wants to be where they're guarding. Duh.
And if that fails, well, I'm pretty sure if he's feeling merciful he can just slaughter them.