I can speak from experience watching my wife go through this. Even if you know the person well please don’t assume that someone can’t or won’t go because “oh, they never do” or “they can’t handle [the activity or event]”because of their disability. Invite them and let them make that decision for themselves and if the answer is still no don’t make an assumption as to why. They don’t owe you the full explanation and I bet they do wish to share in that time with you.