thank you for trusting us in this critical situation.
As per you explained your aunt's situation, when to perform the surgery will be totally the surgeon's call who is attending your aunt. and yes presently due to low HB and some kidney dysfunction
doctors are waiting for her to be prepared for surgery. so i would suggest you to have trust in your doctors attending your aunt.
The situation after the surgery means the post operative condition of your aunt will definately depend on how her body copes with the surgery. since as you told she is having some other problems as well.
So exactly how her post operative phase will be ...is difficult to comment on.
kindly trust the team of doctors who are treating her.
give her strength and motivation.
i hope this helps you,
wish her good health