How would you react with the grandparents?

My kids were excited that their grandparents (my father and step-mother) were coming out to visit. They live far away from us but flew in today. I found out that they were just 10 minutes away from our house but they didn't bother to stop in to see the grandkids. And when I called and spoke with my dad he said they won't be dropping by at all but he said we should pop by where they are staying. I feel really odd by the behavior and asked if they might meet us at the zoo or another local park but they refused. He is acting very rude because I told him we can not go out because his granddaughter is in school? He was demanding that I take her out for the whole week which was obviously a very bad idea and would put her behind in school. I am furious but I don't want to have a fall out with them. We are not very close and they rarely send them gifts. Also they promised many times before to my daughter that they would come and see her or would send her a gift but never followed through with it...