If the HVC Antibody test comes back positive, the next step would be to have a HVC DNA PCR test done. This is a test that looks for the actual virus instead of the antibodies and will tell how much of the virus is in the blood.
About 25% of people who are infected with Hepatitis C are able to fight it off on their own. The virus is removed from the body, but the antibodies will remain forever. So, it is possible that you can test positive for Hep C with the antibody test but not actually be currently infected.
Your father's doctor may also want to run liver function tests to see if his liver is operating normally. If the DNA PCR test shows that there is active Hep C virus in your father's blood, you may want to consult a liver specialist (hepatologist) as they have more knowledge about Hepatitis C and the best treatment plan.
Try not to worry too much as their are now a number of very effective drugs for Hepatitis C and the prognosis for Hep C patients is much better than it was just a few years ago.