No the black hair guy didn't die the blood was from the demon he consumed, the sister and father did die from the sicknes of the curse
Assuming your talking about the first story......spoilers
The father and sister survived after being cured by 'Setsu' (originally the dark haired guy who became the light haired guy after fully consuming the banshou? demon)
Sets had made a acknowledge the adopted son and initiated a contract and with him once he was given a new name - the wish being to save his adopted family, once they were save sets would have returned to being a bone/tooth
This is seen again with the grandfather who initiated a contract with setsu(ko) and THe wish that he didn't want to be lonely after his wife died - when the grandfather's wish to not be lonely was fulfilled by his child and grandchild(the protagonist) came to live with him sets returned to his previous state (returning to a bone/tooth to conserve life energy to further protect future generations)
In the end the protagonist ends up calling upon him again wishing to cure his disease originally - the wish changing from wanting his disease to be cured to wanting sets to see the world and be with him always sets ends up not disappearing
(Long story short --- the curse is bloodline related so the couldn't have died at that time because if they had there wouldn't be a story to begin with.....but from what I understand the lifespans vary so they probably didn't live too too long after??)
Hope this helped...
Iam lost ,, the father abd the sister what happened to them? And thr long black haired man did he die?there was blood