Trip to Mom's to help her out

Phase I was OK. I have never seen her is so much pain. Yet, I had to help her the way she wanted to be helped. Her life maintenance routines are quite different from mine.
Within the first few hours we fought. How do you make coffee? Coffee is very important to both of us. She has a very specific way of making coffee that I needed to follow. I didn't.
I had coffee in the Boundary Waters Recreation Area the was nothing but coffee grounds thrown into boiling water. No filter between the water and coffee except when it hit your teeth. Your teeth were only a grate that kept the big chunks from going down.
So, maybe I had too much confidence in my coffee making experience. Let it be noted we made coffee the way she wanted. I did not want to see her cry in the first few minutes I arrived. Yet, the basic process of making coffee is the same. You fill a reservoir with water. You hopefully have a filter that fits the machine. You have coffee ground and a way to measure it. Put the decanter under the filter. Finally, you press the start button.
How bad could I have made it? Now mind you I know she is in pain, that is why I am here. But she could not delegate coffee making to me. We are not talking every pot. This was just one pot of coffee. If it was bad, she could have made another pot after pouring mine out.
I had just traveled from Denver to Baltimore on the red-eye. I got a few hours sleep. Not enough. So, I had to set up a network in her house right away to get to work. I thought we could chat for a while, maybe even go the Lock Raven Diner for breakfast. She probably was up half the night in pain. We were both grumpy and wanted coffee. Yet we did not agree.
She started crying when I took the decanter and rinsed it out and filled it with water to put in the reservoir. I should have used a plastic measuring cup. I should have. I didn't know what a big deal it was to do things in different ways. She felt very strongly about using the plastic measuring cup. Felt is not the right word. It was almost religious faith that it had to be done with a measuring cup. Use of the decanter was taboo to my Mom. I didn't respect that taboo.
For the rest of the 2 minutes I took to set up the coffee maker was a contrived struggle. After I have used the decanter instead of the measuring cup, what could I do? It was her concern that I was going to overfill it. The exact reason I used the decanter. You can't over fill the system to create a leak. I did fill it to only 8 cups.
The thought crossed my mind that this was not banter but my Mom crying. Was it due to the pain in the back or me trying to take over her making coffee? Either way, I felt very stressed. If I can't make coffee to her spec, I doubt their will be little I can do that will meet her approval.