On the shelf of the laundry room.
I'm using version 1.4, is it still there in the afternoon, is there a bug that prevents it from showing up if you take too long, or why can't I find it? I have tried going to the bathroom, looking at the tub, and then going straight to the laundry room at every time of the day and I still can't find it, even when trying to interact with everything in the room.
EDIT: Found it, you need to watch tv with your mom and NOT use any powers on her and let her go take a bath and then get caught. After that you will be able to find lavender steam bath oils.