I asked this on another post, but can Trump UN-pardon her if Obama pardons her?
Well this would do 2 things.
1) Eliminate her ever running again.
2) Take Trump off the hook and preclude prosecution.
Note that pardons are not blanket, and I think they have to be for a conviction — so the FBI would need to finish investigation, bring charges, indict, convict — and then have her pardoned.