You can't let your mind mix around "what if" situations because you'll never stop thinking.
You'll always come up with a new feeling or the idea of guilt will continue with you.
This is what you need to know OP.
If you were kind, in any way to her and made her laugh then she doesn't care.
In her mind, she probably knew she was dying and forgot about the negatives.
Do you think she was upset you not showing up?
If you do, then you shouldn't because she's dead now.
She didn't die with the thought of you not going in her mind, so stop beating yourself over it and move on.
Learn from this.
Be there when you can because you never know how'll you'll feel after they're gone.