Hoping this will not be your friend's third C section, women are usually advised to have a longer break between children if they have sections. Presuming it isn't, and she recovers well, she'll be Ok but will need support. Anyone prepared to lend a hand (quietly, not intrusively), and let her get some sleep will certainly be welcome.
I wonder why she had three babies so close together, not my business of course and the pregnancies may not have been planned that way.
Good luck to her 
. You sound like a good friend.
(Thinking about this further, my maternal grandmother had ten children in fifteen years - nine of them were within ten years! One was disabled. My mother was the youngest by five years and when she was small, gran took in one of her grandchildren, a boy, because she felt his parents (son and daughter in law), had too much on their plate. He lived with gran until he was an adult.
Tiny house, no washing machines in those days, coal fires & outside lavatory. Very poor. I wonder how she managed, not sure that she always did all that well but by the time my mum came along, things were easier and mum as the baby was spoiled. None of her children had big families and she encouraged them not to. Hardly surprising.)