I am assuming you like your two cousins. Your mind seems to zero in on death. Do you know why? First you dream of the death and then the "burial" of your two cousins. Have they done something to harm or offend you? Or instead is this just a fear of death, which is quite normal for all of mankind. Come to terms with the fact that you too will die. No one lives forever on planet Earth. If you have deep fears of death, I urge you to find a Belief System to help you make it through your Life, like a belief in resurrection to Life everlasting, or reincarnation, and there are other options also.