The sad fact is that there are dangers everywhere for hogs. Hogs can travel up to 2 miles in a night, so you will see that they are likely to be near a main road in a lot of places. In some ways quiet country roads can be just as dangerous as they may think it is safer to cross and then a vehicle suddenly comes along.
So the answer to your question is: Hedgehogs should be released back where they came from. There they will be familiar with the surroundings, etc.
You might find it helpful to read the following for further information https://www.hedgehogstreet.org/guidance-on-releasing-rehabilitated-hedgehogs/ and also, if you haven’t already, some of the comments above.