How much should a cat that just had kitties eat?

My cat just had babies this past Friday and I'm wondering what kind and how much food should I give her?

She's a stray that loves to stay in my house and also wanders around. She had her babies under my couch and I would like to feed her something good to aid with her health and the kittens.

I'll be passing by a supermarket later and would like to buy her the stuff then.

Thanks for the help! 

Feed her kittenfood _ I'd suggest a good brand and kibbles. Usually it says, on the package, it's for kittens as well as milk giving moms. Make sure you have enough standing so she can go amd eat it whenever she pleases. She'll eat more than usual, and she needs it!