Should Macduff be held responsible for the deaths in his family in Macbeth?
This is a really interesting question to consider. On the one hand, obviously he wasn't the one who ordered the slaughter of his family, yet on the other hand, he did flee to England, leaving them alone and vulnerable. Presumably he thought that as his quarrel was with Macbeth alone, his family was safe. Being a noble man himself perhaps he underestimated Macbeth's evil nature and the lengths that he was willing to go to to secure his power, even if women and children stood in the way.
However, if you analyse Act IV scene 2, it is clear that his wife is very away of the vulnerable position that he has left them in. Consider what she says to her cousin, Rosse:
Wisdom! to leave his wife, to leave his babes,
His mansion, and his titles in a place
From whence himself does fly?
She certainly questions the "wisdom" that leads him to desert them and leave them open to Macbeth's evil plan to kill them. Thus we can perhaps say that Macduff is at least partly responsible, for he could have taken his wife and children with him to England for their protection.