Offset door hinges allow the door to open another inch or more, which is sometimes all it takes, and are a simple and cheap solution.

Older homes can be tough to adapt- small doors, bad angles and halls, etc. You often need to get very creative, and sometimes you need to spend a bit.

For example, another option would be a ceiling-mounted track for a patient lift so you could transfer them in a roomier area and it would move them to where you need.

Or, you can use other options to bypass the bathroom- turn a corner of a more accessible room to a bathroom with a commode chair, brushing teeth in the kitchen, and and using bed baths most of the time.

you don’t say how much narrower but I am going to assume that it
is a 30 or 32 door. One suggestion is to put a grab bar on the door
itself. This way they can go to the door, grab the bar and spin the walker into the bathroom. If they are not steady enough for this move
then placing railings inside the bathroom might be a better idea.

Also check in your supply house for the narrower walkers. I put
two links to online providers as well. Do a search on narrow walkers
for more.

Bravo to you for helping out!

You can purchase a gait belt to put around their waist. There is a technique where you can assist them with walking in and out of the bathroom so they dont fall. You can find more info at this site:

patienteducation.blogspot.com/2009
/07/why-use-gait-belt.html

Good luck and a pat on the back for taking care of your inlaws!