Three young children on your own as you age, is a lot, especially if their behaviour is wanting. You have enough going on with your dh in a care home, and a lively dog.
Nip this in, decide what you can do and stick to it,
We are not responsible for childcare of our children’s children, the parents are .
Your day sounded like really hard work. Decide what you are comfortable with and stick to it.
If you start off low you can always increase if you wish. If you start out doing too much it’s harder to reduce.
Have a good rest tomorrow.