How should i care for a mother mouse and her babies?

Wow you've done an amazing job, well done. Laurie is right. Try to disturb the mice as little as possible. Keep providing food and water and make sure they have plenty of bedding. Tissue paper is fine. If you can, after a few days try and get some of the soiled bedding out without disturbing the nest. When my mice had babies all I could do was clean the tank around the nest. I had to leave the nest as it was for about a week. As mummy mouse is feeding her pups she may need a bit more protein in her diet. Seeds will be great for this as is egg. I fed mine scrambled and hard boiled eggs while they were pregnant and also for around 2 weeks after they has given birth. I hope this helps. Good luck.