Will a mother's wrath befall her son who honored her but did not love her, after she died angry with him and his siblings prayed against him, [claiming] that he was the cause of her death?

The rights of a mother are immense and are not negated by her shortcomings or injustices. Indeed, Allah has commanded companionship with kindness towards parents, even if they are polytheists. So, if you have fulfilled your mother's rights, her dislike of you or her displeasure does not harm you. However, if you have fallen short in honoring her, then it is obligatory to repent and to rectify this by supplicating for her, seeking forgiveness for her, giving charity on her behalf, maintaining ties of kinship, and honoring her friends.