Can they deny me if I passed the test but she said a decision cannot yet be made?

Without additional facts about your case and the specific immigration benefit that you applied for, it is difficult to predict the outcome of that case. A decision will be made ultimately on your case. And if you suspect that your case may be denied, you should seek the assistance of an experienced immigration attorney.

We need more information about what process you are undergoing before USCIS to give you a proper answer. However, any process that you pursue before USCIS can result in a denial if not pursued properly, or if it should not have been undertaken in the first place.