‘Tis the season for some ASD-friendly advice for big family/friend gatherings. I can’t do better than Karla’s visual:
Addition 1: Don’t banish autistic kids to the kids’ table, if there is one. Sitting at a table for the meal should be optional anyway, and if they choose to join, let them sit with the adults if they prefer.
Addition 2: Regarding physical touch, people like it and some don’t, but those who don’t may actually find it painful or disorienting. Ask if it’s OK before shaking hands, hugging, or otherwise touching an autistic person, and respect “no” as answer. If you are the parent of an autistic child, don’t insist that little Johnny hug his grandma. Advocate for him.
I wish you peace and joy, however you may find it!
Life, His Way 
Great advice, if people respected these rules I and others like me wouldn’t be forced to spend holidays alone.