My grandfather has been on hospice for a few months now. He lives at home with my step grandmother and her two adult children. She only has a nurse come in every three days to tend to him. He has not eaten for three weeks and gets less than 5 oz of water a day. He has trouble swallowing. We try to go and visit him and his wife makes it very difficult. My mother goes to visit but she is not allowed to speak to him or touch him per his wife's instruction. She doesn't want him to know anyone else is there. If my my mom goes against her wishes she will no longer let anyone visit. She won't let any of the rest of us visit him either. We want him to know we are there and that he is not alone. Can his wife keep us from being able to visit?
Your grandfather is dying. Your Mom needs to ask the wife if you can all come and say your goodbyes. Mom may want to ask why he can't be touched. Does it cause him some discomfort? In my opinion, a human touch is what he should have. But its wifes house, her husband, her rules. If you want to see him, I would be on my best behaviour.
As has been explained, he is dying. The administration of food and fluids to someone with swallow difficulties results in aspiration pneumonia and an uncomfortable death. Usually Hospice not only assists but they make certain that family visits are comfortable and a way to bid goodbye for all involved.
Your best way to your grandfather now if through his wife. Assist her, offer her your sympathy, your love and your help, reassure her that you will not disrupt anything in his care, nor give your advice (which is not needed here). Help provide her with easy meals or meal deliveries, and help her all you can.
I would respect her wishes. This is also very tough on her seeing the love of her life slowly fading away. It is very exhausting for her physically and emotionally.