If I'm allergic to dilaudid can I take morphine?

Maybe. Dilaudid and morphine are narcotics, but are different substances. It depends on the reactions you have with morphine. If it is a minor reactions like itchiness, you might be fine taking dilaudid. If it is a major reactions like anaphylactic reaction, you should not take dilaudid. Please talk to your doctor for more guidance.
Depends. If the reaction is due to an allergic mechanism, you can. Unfortunately, reactions to narcotics are often due to 'histamine release' 'pseudoallergic' mechanisms. If there is a tendency toward having hives or anaphylaxis, narcotics can bring out the tendency. A visit to an allergist-immunologist may help distinguish the mechanisms.