One suggestion on the 642...have the trigger return spring replaced with a 12-13# Wolf. I would not mess with the main spring to make sure ignition stays reliable but I have replaced the trigger return spring in all my Smiths with 13s and it makes a big difference.
Also...buy mom some life size photo bad guy targets and instead of "target" shooting on paper plates teach her how to just put a round on target asap from handshaking distance out to 15'.
The money that you will save over buying a new gun will buy a lot of practice ammo...
