First off, the entire grid may or may not go down from one EMP attack. Even if it did, it would likely be due to a cascade failure like the one that hit the Northeast in what year was that, 2005? The grid can be brought back online for those areas not directly hit by removing the connections to other regions and supporting only thier own. Many regions that regain their nuclear and hydro power in particular will then begin to rebuild and reorganize and support neighboring regions.
A lot of people have backup generators. The problem will be fuel. But let’s not assume that refineries are going to be down for a while year. And why would transportation go down. If refineries get back up and running, pumps are powerered and tanker trucks can run, what is the problem? Traffic signals? You suggesting no one is going to solve a traffic light problem in a whole year?
People will fix things one at a time. Prioritization and seperation of effort.
The problem is money and credit, or more specifically, the lack of both. In a cashless society, we depend on ATMs and credit transactions to purchase almost everything. Truckers and suppliers depend on credit to purchase fuel and inventory. When the grid goes down for any length of time, we lose our money and there is no credit to purchase anything. No supplies, no food, no gas, no nothing is delivered, and ever if it were, there would be no cash to purchase it.