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'.
I'll add maybe get some laser grips and sight it in. Knowing how to use the sights is important but at close range in a high stress situation the laser sights are a plus.
