Why is my Friend lying & saying she's Jesus Christ?

Sorry, but your friend has had an emotional breakdown. She needs medical and psychological help. Her father's unrealistic perfectionism and expectations have caused her to become (in her own mind) the most perfect human that ever walked the earth. Try and reason with her. Let her know you are there for her, but that she needs to get help. If you believe in God, pray that He would convince her spirit to seek medical help. The Bible shows us that Jesus sought the help of a human physician (Apostle Luke) to minister to people.