I am surprised she let this problem go so far. You have to address things immediatly, I'm sure she noticed her hair problem but she was "TOO IN LOVE" with the wig to stop wearing it.
That is why I tell people, all styles will take out your hair if you are not monitoring and careful.
For me, I can't talk for every black woman in the world but for ME....
If you keep getting braids over and over after a while even with the best of care some people will notice that their ediges are thinning out.
If you wear a ponytail constantly after a while, you might notice that the hair is thinning out wear you put the rubber band.
If you wear a weave constantly after a while, you might notice your kitchen track where you hair might be the shortest has broken off due to the weight of the tracks.
If you wear a lace wig, constantly and are applying glue...after a while your edges will thin.
So the moral of the story and what I have learned to do is 1) inspect your hair and look for thinning AND most importantly 2) switch it up if you wear a lace wig for 1 month, switch to a pony tail for a few weeks,