147 grain - the Ladysmith is a great choice. I hope she appreciates it. The wadcutter as a self defense round does not have a heavy punch, but only a fool would stand in front of one. That being said, wadcutters punch a non-healing square hold in the target and I can tell you from experience that two through the chestplate will drop even a big drunk.
However, that being said your wife will need to practice with that snubby. Both longer and shorter barrels maximize shooting errors. 4" is optimum they used to say and 4" revolvers are good for me but I do like my snubbies.
If your wife practices and gets comfortable with wadcutters, she can put those to good use. HTH. Mikey.