talk to her like you would a child, to make her do things
This can be taken two ways and I suppose it how the inflections were given in the original comment!
I would prefer to think of it as moderating how you phrase things to Mum, choices become difficult for dementia patients. So does the speed and amount of words in a 'normal' conversation. As to 'making her do things', you can't! Mum will still decide what and when she wants to do things.
On the personal hygiene front, that's more difficult!
You will become very adept at 'telling white lies' or alternatively 'lying through your back teeth'
to get a result (ie. we are going to ....wherever... I've run a bath for you, Mum might take you up on the offer, she very well may not, but at least you tried.) I have gone through buying baby wipes, toilet wipes, buying deodorant sprays ('because I thought you might like one Mum'), using my favourite perfume on her like it's going out of fashion
We now have a lady who comes to help Mum dress and wash/shower in the mornings and Mum accepts this, where she would never accept it from me or Dad. So it's a case of do what you can at that moment and keep trying
Your Mum is still Mum at the end of the day, you will know as time goes on what's right for her, go with your instincts and you won't go far wrong.
Keep posting, the folks on here are great, and a terrific support. Take care.