my wife is wondering if there is a spell specifically for stealing or compelling someone to give her something life convincing the guard to give he that mag key and him to fell great about doing so afterwards

I'd suggest that mind control, control emotions, and influence are your friends on this one.

Magic Fingers, if you have the Palming skill.

Alter Memory perhaps. "Can I have that thing back that I lent you?"

Hot Potato will make them not want to hold onto the item.

Ultimately there's no Steal spell and for persuasion FuelDrop covered it.

Most of the spells have been covered already - I would focus it down to mind probe to get information, control thoughts to get the guard to do something immediately, influence to get the guard to do something later, and alter memory after any of the above, so that the guard doesn't remember it afterwards.

One thing to be careful of is security setups where the guard is tied in to the overall surveillance (a security helmet with a camera, etc.). Fooling the guard won't do any good if the people monitoring the guard notice something suspicious. But that falls under the "do legwork first" category.

IT's also the sort of magic that gets peoples antsy about mages, so expect quite a bit of cold shoulders and peoples dealign through a drone rather than in the flesh if it gets widely know you pack that sort of spells and are fond of using them.

I would use a combination of Influence spell and the Commanding Voice power.

First you implant the suggestion and then you use Commanding Voice just to be sure.

Commanding voice doesn't work that way. It is more of a Bene Gesserit voice kind of thing - you command someone, and they instinctively obey, or at the very least freeze up. It's incredibly useful, but it is not a subtle manipulation, and it only affects the target's next action.