If your dad is a believer then the best thing is for him to find some Bible verses on healing and pray them for himself every day. God makes so many promises for our healing. I know people who were healed of cancer this way.He must not allow himself to doubt Gods word on healing or speak our negative things, and you need to all do the same. Also getting good books or cds on Gods healing power will help build up his faith. Joel Osteens mother was given only 3 weeks to live with cancer, and after doing the above she is still here and was completely healed. That was about 20 years ago.
I would never seek new age treatments such as homeopathy or acupuncture. Gods word is the way to God. There is real power in praying the scriptures, I have seen this myself in other areas of my life.
Therefore I tell you, whatever you ask in prayer, believe that you have received it, and it will be yours.