Is she am indoor only cat or mostly outdoors? Cats , by their nature are mostly fastidious groomers (unless sick) and rarely need help from their well intentioned humans:-). If she's feral, I doubt you can do anything. If she's gentle enough to get her in a pet carries you might have a vet give her a mild sedative so she can be bathed, but for now with 5 day old kittens, she's their lifeline and her total focus is on them. I'd let her work on grooming herself as unpleasant as it may be for now. She's not going to want to be separated from them, especially for a bath!
Do you have declared cats?
Cats have the ability to clean them selves. Give her time. She provably adapting to her new life.
There's pet wipes that you can buy in some pet stores. Call around and ask who has them and how much.
Phone your vet.
Shower with a closed door or wet towel wipe down.
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