Depends if she has an auxillary clearance or not (lymph nodes removed). WIth the aux clearance, its a more painful procedure and recovery, without its much easier.
I had mastectomy & aux clearance in March. It was 3 weeks before I could drive, although surgeon told me I could drive after 10 days - I think I recovered slowly because I'd just finished 5 mths of chemo and was very debilitated.
It was 5 weeks before I could lift DS (23 mths). I had 4 nights in hospital, but could have come home after 2 nights - she will be able to do basic stuff for herself when she comes home, like shower and dress (button up shirts, not over the head stuff initially).
The physio exercises she will be given are very important - she needs to keep on top of pain relief to enable her to do the exercises several times a day.
She'll need help with laundry and cleaning, assume for 6 wks. Best if she's not trying to cook meals initially too.
Good luck, I hope she recovers quickly.