You try the beastman floor, thinking that your mother might be on that floor, so you press the button that goes to it. You did remember a guard saying something about a hellhound escaping, so your mother was probably hiding from it on that floor. You press the beastman button, which takes you to that floor.
After passing down three of the floors, the elevator lands on the beastman floor that you wanted to search for. As the elevator doors oven, you find that the entire floor you were on was half forest, half jungle. It was as if the mammal monster girls would be lurking in their rooms. You then notice a trail of burned footprints which might have come from the hellhound that was living on the floor you were on, and the last thing you find was a dead soldier carrying a guard, with a melted off face.
You then find that the guard was carrying a rifle, that was of course loaded when you shoot it off. You then take the rifle in your hands, and arrive to the next area, that has 26 doors. Each of them have a different monster girl inside of it.