You can only give it to her (without an FFL) if you die and leave it to her in your will.
Otherwise, you can ship or deliver it to an FFL anywhere she can get to, and she can pick it up there. Except that "anywhere" doesn't include Massachusetts, because we suck.
The easiest thing would be to box it up (without ammo, obviously) and ship it via USPS to an FFL in GA who will accept shipments from individuals. (some won't. Not because of a law, but because that's their policy) If you can't find one that'll do that, ship it to any FFL she likes through an FFL in MA. (which will cost you twice)
You can't ship *handguns* via USPS, only long guns.