First off, how big a litter is it? Second how old are the babies now?
Next, Oxbow is fine, toss the seed mix (bad for them)...give her oxbow with a lot of extra protein sources, like egg, fish and chicken. Lots of veggies, not much fruit because you don't want her to get diarrhea when she's nursing (mom's are prone to it)
She will need Out each day to run off some steam, when the babies are a week or less then I let my rescue moms run twice a day for 20 mins each. After that they can be out 30 mins to 45 mins...when they hit 3 weeks I let them out an hour at a time trying to time it that she's just finished nursing.
The babies will start sampling whatever mom is eating, often sniffing her mouth or taking something from her mouth...its a baby rat's way of learning what is safe and good to eat. Then they will start really eating, and you will be shocked at how much your little family consumes...at first give them Baby cereal, small easily handleable veggies like thawed frozen corn and peas, leaf lettuces, etc. Their jaws will strengthen quickly and they will start gnawing on the big hard stuff
I socialize babies every day from birth on...just a very short time until their fur grows in (5 days or so) and they can keep their body temp up. I handle them gentley and feel them all over, dangle them for a moment, put them on their back and pretend to check their teeth and ears...anything you or a vet may need to do later in life you want them to be used to. Once those eyes open, they will start seriously zooming and a good sign is when they run for you instead of away from you LOL
Boys should be removed from the females (mom stays with girls) at 5 weeks of age. I now prefer to move MOm and girls out of the cage into a new one..the girls get to keep their mom, and the boys lose their mom/sisters but keep the familiarity of their cage.
Do you need help sexing? I got pics with diagrams for that
Just let me know.