Navigating through magical darkness

This issue came up when the party’s warlock cast Hunger of Hadar upon some enemies. She argued that because they were within magical darkness, and blinded, that they should not be able to immediately run out of the spells area of effect without having to make some form of a check to know where they were going.

What are the rules for moving when you can’t see? Should an enemy be able to just walk out of magical darkness, or should there be a check that needs to be made? Visual below:

A grid map of a Warlock who has cast Hunger of Hadar on two enemies

Should they just be allowed to run towards her, or at least be able to escape? Or should they have to bumble around in the dark in order to try to get out, with ENEMY 1 potentially walking away from the Warlock in difficult terrain, thus being trapped in the spell for another round?

In the meantime, for less wise enemies, we would roll a d8 and they would walk in the direction that they rolled. Until I find more definitive ruling, we were thinking about the enemy having to make a survival check/wisdom saving throw opposed to the Warlock’s spell save DC, and imposing the d8 random movement if they fail.