Do nurses have the right to know the condition of her patient especially when her patient is HIV positive?

IMHO--yes. This topic could be debated for days. Some people will say yes, others will say no. But you must consider every patient to be HIV positive, because the patient could be HIV positive and not even know it. That's why it is called universal precautions. It's also important in cases where the nurse is pregnant and the patient has some other infection.
Yes. A nurse should know all the relevant conditions his or her patient has to be able to provide the best possible care. All healthcare workers should practice universal precautions with every patient though.