Sorry about your loss. That’s a tough situation for sure, and it sounds like you have (understandably) a lot more grieving to do.
Yes, kind of a bonehead move, although the official probably does not know your situation or have a good set of guidelines on when to bend the rules and when not to. Whether or not the race recognizes it or not may seem like a big deal now. No matter what the race officials do, the reality is that you WERE there, and you DID take carry her with you through the race and across the line, and you DID honor her.
I can’t walk in your shoes, but I’ll offer that it’s maybe even better that they disqualified you. Because she was way more important than official results. And it probably felt like you weren’t really there without her being right there with you this year. I know that is a weird way to think, and I am not asking you to agree or disagree with it.