what does this dream of mine means?

Keep in mind that dream interpretations are cultural. That is to say, if you go to another culture it won't be the same interpretation. My point there is that I doubt it will happen. To put it very bluntly, your close ones probably have the same odds as anyone else dying, so there is nothing to worry about in terms of having that dream mean anything certain. Also, the way dreams work out are influenced by the impressions of the person themselves, which may or may not be congruent to the culture... or it could be random. The subconscious is a strange place. So don't worry too much about it, I think.