No will, no gardenship No durable power of attorney incompentent nonresponsive what to do?

as of july 2 2014 my father had a stroke he was semi responsive in the beginning and now he is in a semi coma non responsive state he cant write talk and barely opens his eyes..... he has no will and my mother cant get a document stating that she is his power of attorney being that he is not able to sign.... is she able to get guardianship over him? we need to handle important things as far as getting the car back to the dealer from whom he leased from and not have to pay the rest of the payments and to fax over to the insurance company for the car.... we are worried about when he passes estate will take the house from my mother he also has brothers and sisters alive but they would decline of having a share of the house..she is also his beneficiary on his life support what is that we have to