In a view, how can I add a column rule that highligh an specific task based on 2 conditions?

You can add multiple rules to the same column, however, they will act independent of each other (as if they are OR statements). There isn't currently a way to leverage AND statements for column rules, although I do think that is a great idea!

If you can submit that as a feature enhancement to the Ideas tab, I can surface it to the Workfront Product team for additional review.