My mum has vascular dementia and alzheimer. i saw her 4 weeks ago she could walk slowly talk and cook. is she getting better?

Complex question: People with alzheimer's do not improve as far as more brain cells overall though every day can be different. If one has an acute stroke then there can be improvement for a few months after the stroke though overall there is stepwise decline. However, just because you have dementia does not mean you cannot do things. People with early dementia still cook, clean and do many other things.

Unlikely: Both vascular dementia and alzheimer's disease are progressive diseases. People might have better days but usually do not get better.