Ok .40 cal which is very close to 10mm is great choice for self defense against a human. Against a bear I wouldnt advice anything less then .45 ACP. Which that being said he would be better off carrying an revolver with .357, .45 long, .454 or what have you. Sure revolver doesnt have as many shots but wont fail cause of weather conditions your father will face while hunting. Also you want a steel frame gun for this type of carry, cause if the gun runs out of ammo or semi jams then he can still use it as a club which heavy blows to a bears nose has been known to chase them off.
One may think that a bear wouldnt be so hard to take down but you take a deer. I have deer hunt for a long time and have seen deer run 100 yards after a clean shot through the lugs from a 30-06. If a deer can be that tough think of what a bear can do.
With all that factor in if you are still wanting a semi no matter what I would have to say Rock Island 1911, .45 ACP 8+1 rounds steel frame for $350-450. For a revolver I actually like the Taurus revolvers for the money they are hard to beat and highly recommended in the hunting sports.
P.S. - I believe last year there was some laws passed that allow bow hunters to carry a defensive firearm while bow hunting. Check with your state laws as that could just be in KY but I remember reading something of the sort in a NRA e-mail.