Gramma cat no doubt just came to voice her opinion of the interloper and make sure the cad knew who was boss.
Expect some fun in the next few days, watching the younger cats interact with the dog. It should be quite fun.
That is precisely what it looked like.
The dog is a cute little thing; I just have to remember to watch for land mines when I go outside. I stepped in one of his "presents" and didn't realize it until I'd already tracked it through the downstairs.