Accidents do happen. If your elder were to fall in the bathroom, could you get in? Easily?

Do you know how to open the door from the outside? If your older bathroom door has a key lock, be sure you have an extra key that you can reach quickly. Tape it to the wall above the door, where it isn't easily visible but it's handy. If you have a newer lock with the little hole on the outside, try using an opened clothes hanger - stick the wire into the hole while you turn the knob. Practice this before you need to.

You can reverse the doorknobs, so the lock is on the outside and no one can lock the door from the inside. If you're really handy, you can reverse the door, so that it opens out instead of in.

Best to go take a look now...You really don't want to have to start messing with hinges or beating down doors if someone inside the bathroom is in trouble.