Of the usual polymer pistols (glock, Xd, Xdm, FNP/FNX, etc), the S&W M&P has mild felt recoil. My full size 9mm M&P with safety has milder felt recoil than my Glock 34, Xdm 3.8, Walther P99, and Kahr K9.
If the trigger reach is OK for her hand size, then M&P maybe the way to go.
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I use to not like the M&P. As I use it more at the range, I am liking it more. Mine has an Apex sear and Apex firing pin block. The OEM trigger setup was OK -- the Apex FB allowed for a smoother trigger pull. The Apex sear allowed for a better/cleaner/lighter trigger break.