Not sure that could work. If you, as executive, "faithfully execute the law", how could you pardon yourself? If you could, you could commit all manner of murder and mayhem, and just pardon yourself.
She didn't want to answer as it could become an issue before the Court. Wise move. She is clever.
Federalist 74 deals with pardoning powers:
https://avalon.law.yale.edu/18th_century/fed74.asp