Dreams about death are not necessarily omens of impending death or a warning that anything else bad is going to happen. They usually represent angry feelings that are suppressed within our sub conscious.
If you dream about a member of your family or a loved one dying, then it usually means that you are lacking a certain quality that they possess and you wish that you had.
If you witness someone you know dying, it could also mean that your feelings for that person are dead or a significant change between the two of you is occurring. It could also mean that the death of the relationship is occurring, but you are denying it i.e. Repressing those particular emotions to avoid acknowledging them.
If someone is just trying to kill you and your family but you are not asleep long enough to see them die or you constantly evade them, then this could mean that you are trying to protect your family from something in the real world.
Remember that each person’s or each book’s definition of a dream is different and neither is necessarily correct. Dreams are projections of our sub conscious and because they come from this part of our mind that we cannot control, there can be clues within that can explain certain things about them. But a certain dream you have is definitely not something that you should dwell on or worry about.