I'm sorry for your families loss. My thoughts and prayers are with you and your family.
I think leaving your puppy in the bathroom will be fine. She's the same age/weight as my Bella and I ended up leaving Bella alone for 3 hours a few days after I got her. She was fine when I got home, I was the one that was having heart failure.
I originally used a playpen to keep her in because she was so tiny, and then Bella turned into Houdini and could always manage to get out of it. The last time being I had left her in it for my quick trip to the doctor's office. I came home and looked in the playpen and no Bella. She had escaped and I did the "where's my dog"....and she had escaped to my room and was waiting for me there with this cute little expression of "see what I can do mom"?