I don't mean to upset you but it sounds like fiancee is either very insecure and feels threatened by the relationship with your daughter or he is jealous of the time and money you spend on them. This not a good sign. He should be able to appreciate the relationship you have with your daughter and grandchildren and understand that that does not take away from the relationship with him. Emergencies arise with family all the time. I could see him being disappointed but he is taking this too far. If he is upset now that may become an even bigger problem later. You should not have to choose which is probably why daughter is upset. No one wants to see their mother have to choose between their partner and their children. I fear that the further this goes the more distant your daughter could become. In addition, the silent treatment is a purposeful ineffective way to solve problems. That is problem number two. This is fixed pretty easily. For that get a copy of Mars and Venus Together Forever.
Give this some thought so you make an educated decision.
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I am the male in this situation, would your answer be the same if my fiancee is a woman