Your MIL looks great with the short hair. I get the idea... it's not "feminine", I say the Heck with that... I LOVE the look of a lady with short hair and a HUGE smile. You MIL has all that, and more... she looks absolutely TERRIFIC.
I hope she is continuing to feel positive about the experience and wanting to take her hair shorter and shorter. She looks pretty radiant and when she embraces the sly, she will look AMAZING.