Is it haram to dance to music that has nice, halal lyrics but the beat is fast? And is it okay if I’m only dancing in front of my husband, or even my daughters and grand daughter? The lyrics are not bad, but the beat is fast. For example a happy birthday song that is remixed to be faster and more exciting?

It is allowed as long as it is not accompanied by haram music. The criteria for permissibility is that it should not be suitable for gatherings of play and amusement.