I'm taking my two daughters and my son

[No Vested Interest]

4. If your aunt is failing more quickly than you or she expected,

it would be worthwhile for you to go on your own, with the thought of bringing the children at a time when/if she can cope with the thought of four people coming to her.

To an older, ill person, several people, some of whom are unknown to her, may be more than she feels she can handle.
You can judge that when you visit with her.
She may also have some things she wants to say or tell you that may be harder with a larger audience.

As a senior myself, though not in failing health, the energy and stamina required to prepare and host four persons would give me pause.
I know how much you want this for your children, and it is important if it is doable. Sometimes we have to accept the imperfect rather than miss the entire occasion.
Hoping for the best for you, auntie, and children.