put a bolt up high on the door on the outside so you can lock it.
put a play yard around the ladder
unscrew the ladder and put hooks on top of it so you can take it on and off during the day
let her climb up - if she falls off, will be a good learning experience (not really LOL)
i have a very climby 21 month old, she will figure ways to climb even with no ladders, i feel for you.
patty is being very hoity toity,most of us will let our toddlers wander around the house in safe rooms, you cannot watch them every second.