I'm a firm believer that you have to get your head in the right place before you are ready to lose weight. I suffered most of my adult life with being overweight and the pain that that brings, SW a few times, lost a few stone then put it back on and more. Then one morning after a year off of any sort of diet, my head clicked. I was ready to feel better. So joined SW again, lost 4 stone, then it stopped working so I started cal counting, and lost 2 more stone and am now a 10-12 whereas I had always been an 18-22 and at 5ft believe me that's a strain on your body.
So what I'm saying is she's not ready. When you're ready your motivation doesn't let anything, any tragic life event, get in your way because you have found your reason and you're sticking it it.