re: SS and retirement benefits tax question

If I understand your question correctly, Spouse A's Social Security benefits should not be reduced when Spouse B passes. Spouse A should receive their full Social Security benefits and any pension benefits from Spouse B's pension plan.

If it had happened the other way around, if Spouse A had passed first, Spouse B would get their own pension, but any SS payments from Spouse A's SS would be diminished.

At least, that's how I read it. There are caveats for different scenarios, so this would be a good question for a retirement professional.