My daughter is a green card holder. Currently in India. Has been gone for almost 10 months. Due to health reasons she can't comeback until next year. What does she have to do to come back? What forms are to be filed? Where? And when?

So she will have been outside the U.S. for more than a year before she can go back? And she didn't apply for a re-entry permit before she left the U.S. Then before she can go back to the U.S. she will need to apply for an SB-1 returning resident visa at the U.S. consulate. She will need to show that her not returning was due to circumstances outside her control. Health reasons as you mentioned should qualify.

In the unlikely chance that that doesn't work, you will need to apply for a green card for her again from scratch.