Hi Rosie, So sorry to hear about Mum.Stroke is devastating for her and everyone involved. Three weeks is very early on in the post stroke process. I am 19 months post stroke and the first weeks are the worst. Basically, it was,for me, an out of body experience abou which I remember very little.
Currently, doctors will be monitoring Mum and assessing her needs. You do not say how old Mum is. Mine hit me at 73. The general rule of thumb is that the younger you are, the better the chances of recovery, but no two strokes are the same. Strokes also vary in impact. Mine left me with left side paralysis, but I could speak and swallow.
The human brain is amazing and can,and does, re-wire itself. It finds new pathways to the affected areas and this can lead to involuntary arm and leg movements. I had quite a lot of involuntary leg movements, but they did not scare me. It meant life was coming back to the limb.
Try to encourage Mum all you can. She will need grit, determination and willpower to move forward. I did all the physios asked of me....learning to stand, walk again, tie shoelaces and wash and dress myself. I can now walk with a stick, cook, bake and make jam. I can even go away on short breaks. Unfortunately, most of us get post stroke fatigue and you cannot fight this. Mine hit on day 2 out of hospital and is still with me. My afternoon nap is due soon.
It is a long, hard road back to being better than you were, although I cannot do many things I used to. Recovery is ongoing and can take years. Mum will not be allowed home until she can manage and it is usual to go on a home visit so that needs can be met and adaptations made. Age UK put in an extra stair rail, hand grips and a seat in the shower. This was done free. Support,however, varies from area to area. I also had six weeks support at home from the Community Stroke Team.
Others will give you for advice. For the moment, I wish you and Mum all the best.