Does a father's anger at his daughter a day before his death mean that God is angry with her, and what should she do to ease her conscience?

The status of parents is great in Islam. Righteousness towards them is among the greatest acts of nearness (to Allah), and disobedience to them is among the greatest evils. You must repent to Allah for anything that contradicts filial piety. If your repentance is sincere, Allah will be pleased with you, and so will your father, even if he died displeased. Your duty towards your father now is to honor him by supplicating for him, giving charity on his behalf, and dedicating the reward of good deeds to him.