I'm very sorry about your brother. What an interesting dream though! I really do believe those who have crossed over can visit us in our dreams. John Lennon explained it pretty plainly, "I'm not afraid of death because I don't believe in it. It's just getting out of one car, and into another." The thing that trips a lot of folks up about dreams is often they're metaphors that have to be deciphered. It sounds like your Mom was gifted in that regard. It could be that whatever dimension or realm the those who've passed over are in is so different from our reality that ideas don't always translate perfectly between the dimensions.