Sending major <<<<<<vibes>>>>>>> for you, your friend, and her family.
I had a stroke last year at the age of 31, so I can tell you that strokes are not caused by brain tumors, so don't be concerned that that is the case. In my case, it was a combination of a couple of things that caused my stroke. It turned out I had something in my blood that made me more susceptible to forming blood clots, as well as a heart defect called a PFO (patent foramen ovale) that made it easier for blood clots to get up into my brain. I had no symptoms my whole life, but a few months before I had the stroke, I started taking birth control pills for the first time, and because the pill raises the risk of blood clots, it pushed me over the edge and I had a triple stroke that permanently damaged the part of my brain controlling vision.
The good news is I am still here and living a normal life, and so I can tell you that people can and do recover from strokes. Depending on how the stroke has affected your friend, she may need physical or speech therapy to get her back to her old self, but people do recover. If you want to PM me to talk about this, I am more than happy to listen and to answer any questions I am able to answer.
I'll have you and your friend in my thoughts, you can be sure of it.