Can I get my father legal status if he is ill?

Unfortunately, the fact that your father re-entered the country illegally will likely bar him from reopening his immigration case. I would also need information regarding his ties to the U.S. and country of origin to assess what relief, if any, he could seek in reopened proceedings. However, his second illegal entry makes it highly unlikely he could adjust his status and the case will not be reopened solely for the purpose of allowing your father to seek medical help. Your father can receive treatment in most places in the U.S., but your family will likely have to pay for the treatment.