The answer is A.
You devastated the planet and all cardies cheer up with renewed vigor
This is incorrect. I had the same question and received an official response back. The correct answer is B. Here is the email:
Hello - we had a question with the Cardassian expansion, specifically with the card "Anexxation Protocols" which reads:
"When Invading a Planet, a Total Annihilation result counts as a Successful Invasion"
So in an Invasion, I roll hits equal to the number of nodes, is it considered a Successful Invasion and I replace the control node with my own?
Thanks for the email,
Yes that is correct.