Glad that your daughter is using the site to learn! Most of the time what happens in this situation is that the student is relaxed holding the bow, but then they grab harder as they are using pressure to put fingers down in the other hand. Think of this similar to rubbing your stomach and tapping your head at the same time. Your daughter should keep the bow moving the same speed, and not put any more tension (hold) into the bow.
The other thing it could easily be is that your daughter isn’t putting enough pressure into the strings. Try to have her use the tip of her fingers instead of the fat of the finger to put pressure down. To test if this is the problem, try having her pluck a string, and see if you can get a clean sound while having down finger pressure on a string. If you get a dead sound, then she isn’t pressing down properly. If you hear a fine ring of the note, then finger pressure might not be the problem.
My suggestion would be to have your daughter start doing drills that I have in the Fiddle for Dummies video area. Anything from Chapter 5 are the best drills that I have come up with to help beginners. The next thing would be post a video in the video feedback forum. This will allow me to tell you exactly what she is doing wrong. You can post a video to Youtube, and even take the video from your phone.
Hope that helps!