Not sure what to think

So I messed up. I forgot to mail HH's birthday card until the day of her birthday. I truly meant to call her and wish her happy birthday (she may be psychotic and mean, but she is my grandmother). However, right as we finished dinner, we had an emergency call from the neighbors. My neighbor has been battling cancer for 22 years. She's gone into remission a few times, but it always comes back. In October, she had brain surgery to remove a tumor. Several months of therapy later, she is still experiencing seizure-like symptoms. After a long day at the hospital, she fell trying to get up the stairs to her house (therapists WANT her doing stairs, hence no wheel chair ramp). Her wheel chair is impossibly heavy, so the neighbors called for help carrying it and her up the stairs as neighbor's husband and daughter couldn't quite manage it. DH and Dad were both out, so that left me. I can lift about 40lbs when walking up stairs. Obvious solution is to carry neighbor up separately from her chair, but she is so exhausted that she can't assist and we were afraid of dropping her without the support of the wheelchair. So I proposed that the neighbor's daughter and I take the bottom of the chair while the husband took the top. Working together this way, we got my neighbor and her chair up the stairs and into her house. In all this excitement, I forgot all about HH's birthday until after 9PM. I called HH at 10 the next morning, got her machine and apologized profusely and wished her a happy birthday. Tried 2x more to get ahold of her, but kept getting the machine. Dad gets home from his weekly visit today, and tells me that she was snippy with him because I forgot to call on her birthday because the neighbors are clearly more important to me. There is a grain of truth to that statement, which is probably why it hurts, but at the same time, I owned up to what I did wrong and apologized. What more can I do? Tell the neighbor, "Would you mind waiting out in the cold for 10 minutes while I call my grandmother and wish her happy birthday?"