How do I Instantiate a Prefab to align with the closest object?

Alright I may be doing this totally wrong, but I have these empty objects that are basically set up in a grid, I want the character to be able to Instantiate a bomb and have it align itself with the empty object. The character needs to be able to walk over the empty object, so it cannot have a collider.

I'm just really stuck, I just started going in depth with Unity about a week ago.

If you need a reference on what I'm talking about, think Bomberman, how when you place a bomb, it get's placed on a grid.

Any help is appreciated, thank you!