Does Adelaide Kane (who plays Cora) will come back for the second part of season 3 ?

yes she is coming back to the second part of season 3 whitch is the winter season starts jan. 6

The only way she wont come back is if they kill her off on the show... She is in the hospital right now so hopefully nothing will go wrong with that... If they kill someone off in a TV show they get fired in reality.

Their have been some spoilers that Cora will be going we just don't know when. But she probably will stay for the second part because I saw a trailer and she looked fine so idk

Not if the pilot she filmed for a new show on the CW does well and gets picked up. Then she'll be too busy to be on Teen Wolf.