As a southpaw, I use a Sig P220 with the magazine release set up for the right thumb. I reversed it once then reconverted it as it's normal for me to use my index finger to drop the magazine. The decocker is operated by the trigger finger.
I'd consider the CZ-85 Compact as it has ambidextrious controls and feels very comfortable in smaller hands. BTW, the XD is also an excellent gun.
Whatever gun she chooses, have her practice one handed operation and non-dominant hand operation. This includes reloading drills and tap-rack-bang with one hand. The more familiar she becomes with her gun, the more confidence she'll have in herself with it. Kudos to her!