My daughter has a vitamin b-12 level of 900 to1100. is that way too high? and what should she tell her doctor to do?

Slightly high, test: Normal B12 levels are up to 900 so your daughter's are slightly elevated. High B12 can be caused by liver disease (cirrhosis/hepatitis), kidney disease, myeloproliferative disorders (leukemia/polycythemia vera) ; occ. Diabetes ; obesity. It doesn't cause these things but is caused by them. Since it's only slightly elevated she may have none of those but her doc should evaluate for possible causes.