If the driveway turns out to be level, and tar isn't in the cards, I would suggest scraping out whatever crap is currently covering the joint. Old caulk, mud, leaves, whatever. The only thing you want there is the driveway, foundation wall, and the gap. If the gap itself is deeper than 1/2", you will have to fill it with either mortar, or a backer rod until it is 1/2" from the surface. Fill the remaining gap with a polyurethane sealant, such as OSI Quad or Loctite PL. Here is a YouTube video demonstrating this method with backer rod: https://www.youtube.com/watch?v=5Hcx17cQU9Y