Your door should be a solid door, most codes require egress doors to be solid. If that's the case, add some lateral stiffeners, think the gates to a castle, big ass board to keep them secure.
Measure inside to inside of your door frame, basically the width of your door. cut either a 4X4 or some square tubing to this dimension, go from the outside with the carriage bolts, one set about 1/3 way down from the top, the other set 1/3 up from the bottom. BOLT these to your doors, add some heavy brackets, U tubing works great, so that the opening is facing up. When your door is closed you simply place a board, or piece of tubing across the entire door jamb, you'll be securing to the king & jack studs on both sids of the door. They won't get in, even if they remove the hinges, the door isn't coming off unless your cross pieces are out of the slot.
Yeah, it sounds complicated, you want I should come out there and do this shit for you?