The .38 Special Speer 135gr Short-Barrel Gold Dot +P is probably the top performer in snub loads right now. As stated before, very well-proven load in the field. It's my first choice and what I carry in my 642-1.
I'm also a fan of the FBI load. Been around a long time and also well-proven. My preference is for the Buffalo Bore standard pressure version, but I would also go with the Remington version.
While both of those loads generate noticeable recoil, a steel frame can go a long way towards taming that and making it controllable, as well as suitable aftermarket grips that fit your wife's hands. Since this is going to be a home defense gun, you don't have to worry about the concealability of the grips.
148gr WC also make an excellent choice, especially for someone who's not that experienced with guns. Light recoil, relatively low noise, and has the potential to cut a full-caliber width wound channel with adequate penetration. I keep some on hand for my 642s.
Of course, this is dependent on finding said ammo options. If you can't find any of these options, I'd suggest looking for whatever standard pressure ammo you can find, either HP, WC, or SWC. Sometimes we just have to do the best we can with what we have or can get.
Just my non-expert opinion.