On the one hand, it is due to your memory of the state and existence of your family before their death.
Is your family the cause of the disease? If so, then the state of the acquaintance in the dream is seriously ill, indicating that his family was seriously ill at that time.
You rushed to his side, and he died, reflecting that you felt it was a pity to spend too little time with your family.
On the other hand, I think this acquaintance also represents your own inner vulnerability.
The death of your family may be a great blow to you, although you may be strong on the surface.
There are no other suggestions. Dreams are also affected by this incident, reflecting a feeling of helplessness and sadness.