Hi,
The best way to do that is to use colliders, since it's on a grid, set one collider on each adjacent grid and attached this to your player, then as the user will move or enemies, enemies and objects will trigger on them colliders and you'll know where they are located compare to your player ( because an enemy collided on the left collider, or the front collider, etc). It's super easy and very efficient.
If you don't get what I mean, I can do a quick example.
Bye,
Jean