Case A (blue) would be to set the parent parameter every object has, wich also can be found in Object Properties > Relations > Parent
For a onetime operation this could also be done via shortcut Alt + P or python.
Case B (green) does not parent but moves a collection of objects in realtion to another. Here the logic of animation nodes and its potential maybe is more apparent.
Important: for this to work you have to check Delta Transforms in Object Transform Output > N-Panel > Item > Advanced Node Settings > Delta Transforms.
Here you can see were to find the Delta Transform toggle in the Object Transform Output Node: