Assuming you have the block's coordinates i, j, k:
AxisAlignedBB aabb = AxisAlignedBB.getBoundingBoxFromPool(i - 5, j - 5, k - 5, i + 5, j + 5, k + 5);
Then just use the same thing I showed you before.
I need to tick the block to check if there are any near by mobs, i read somewhere i should use a tile entity for this? Should i do that or should i use the built in methods in Block class?