Lady Macbeth and Macbeth do both have a moral crisis, but so does Macduff. When he finds out his wife and children are dead, he does not know what to do. He wants to avenge their deaths, but he also wants to do his duty to Malcolm. He is able to do so, and when he kills Macbeth he does it for his kingdom, not for revenge.
Any time Macbeth is deciding on killing someone for the purpose of keeping himself on the throne is a moral issue. Of course, with each murder, killing becomes easier for him to do.
Malcolm also shows a moral crisis when he tests Macduff's loyalty to him. He paints a picture of himself as wholly unable to serve as King of the realm for his obvious faults.
Lady Macbeth has a moral crisis during her sleepwalking scene where she struggles with the guilt and evil which has brought the Macbeths to the throne and kept them there. "The Thane of Fife had a wife...where is she now?"
Well, the most obvious moral crisis is Macbeth's struggle: to kill the king or not to kill the king? Lady Macbeth has no qualms about the killing, but Macbeth struggles from a both a fear and a moral basis. In his soliloquy, Macbeth outlines all the reasons that he should not kill the king:
First, as I am his kinsman and his subject,
Strong both against the deed: then, as his host,
Who should against his murderer shut the door,
Not bear the knife myself. Besides, this Duncan
Hath borne his faculties so meek, hath been
So clear in his great office, that his virtues
Will plead like angels, trumpet-tongued, against
The deep damnation of his taking-off: (Act I, scene 7)
The reasons listed are that Duncan is his cousin, that Duncan is his guest, and that Duncan has been a good king.
Macbeth goes on to say that he only has ambition to "to prick the sides of my intent". In the end, his wife's urgings and his own ambition are enough - Macbeth puts aside his concerns and moves forward with the plan.