It is of course difficult to diagnose or suggest without seeing her in person. You may wish to consider exploring the following. Many people have a "hump" at the transition area betwen the neck and upper back. Some are more noticeable than others but it CAN be normal. Not saying it is in her case. Some people deposit fat in this area. A moveable fatty area is called a lipoma. It is benign; meaning safe.
There are other masses that can form and this is why it should be looked at by a professional to discern it's composition.