EMP = No Electronics. Bitcoin will be the last of your worries. You'll want guns, ammo, an underground shelter with air filtration, generators with fuel to last a long time, maintenance supplies for equipment, food & water, precious metals, etc.
Very naive to think that in the event of a nuclear war, there will be no internet or no power. The word is a big place. We have many energy generating devices large and small, and connected devices and chips in cars, phones, computers, servers, appliances, satellites, all over the world, below earth - even in space. Gold will be in demand to, but gold is heavy, cannot be easily subdivided, and is very difficult to transport across boarders and new countries, easy to physically seize etc.
The most important thing in terms of preservation of life and safety, (other than in the immediate aftermath of a bombing which happens to be in lethal proximity), will be to be able to move to a safe location and have access to globally fungible assets.