I suggest telling her to relax a little... she may be gripping hard and forcing the bow over the strings, rather than letting the bow do the work. This would create shorter, nastier sounds which may end up sounding sharp.
And also, go easy on the rosin - you only need about 2 or 3 wipes up and down the bow! Too much rosin on the string will end up hindering the sound, so you might wanna try wiping down the string with a clean cloth? The rosin just improves the grip the bow hairs have on the string, making it louder, so no need to go OTT.
What grade is she studying for?