I think it will be SARAH PALIN.
No it won’t. She would bring nothing to the ticket. Boosting the win margin in Alaska or Oklahoma does not get you to 270 EV. And she would not dig Trump out of his broader problem with women voters, because for better or worse, she has been defined by SNL and the broader liberal media (and by some of her own choices) as an unserious person. No independent or democrat would think “I’m not totally sure about Trump, he has no governing experience, but at least he has Sarah Palin with him”. They might however say that about Christie.