+1 for the Kahr, small small SMALL and still in an acceptable caliber
another consideration is a nice light revolver like the S&W 340 Airweight, .357 Mag, 5 rounds, 12oz unloaded.
the debate goes back and forth over what the best thing to carry is, you can carry more rounds with an automatic and they can be slimmer (like the Kahr MK9 which is .90 inches wide) but if you have a malfunction with an automatic when the crap hits the fan all those rounds could be for naught. With a revolver, the only thing that can cause a malfunction is a dud round and you simply pull the trigger again to go to the next round, with an automatic you have rack the slide again, expending precious seconds to reacquire your target or worse you could have a jam that can be even more complicated to clear and all of these things become infinitely more difficult under the stress of a firefight. Unless your wife is a real gun enthusiast who will spend a lot of time training at the range, I would recommend a revolver. And if the .357 proves to be too much in terms of recoil to handle, you can substitute .38 in the same gun and find a load of adequate power that is easier to handle.