Ideally, I wish your husband would go, but we are also unable to make someone do anything they wish not to do.
My sympathies are with you... I suggest just focusing on comforting your mother and aunt and downplay the fact that your husband is not there, or does not wish to go.
In fact, keep that to yourself (that he does not want to go) and graciously hold your own while you are there.
That is all we can do for now, and sometimes a miracle happens and he goes. Otherwise, it's best focus on the most important, your mother and aunt.