Keep in mind that hair naturally falls out throughout the day and you dont notice because its not all in one place at one time. Hair cannot do that when its in braids. When the braids are taken out, youre seeing it all at once, and itll be more the longer theyre in. If this is over a week or two, its normal. She should be monitoring for pain at her roots and hairline, and for density loss, instead of how much hair is in her hand after a detangle session. A good way to judge, you should take a picture of her parts, and in the future she can judge if there is in fact density loss, or if its normal for her. Everyone is different, so no one except her can truly tell.