Is it obligatory to change an evil or to leave the place where it is present, even if that results in the severe anger of one's mother? And is this considered disobedience, when there is doubt as to whether something is an evil?

It is not prescribed to change an evil except after knowing that it is an evil, and in case of doubt, one should ask the people of knowledge.

It is a condition for enjoining good and forbidding evil that the one enjoining it be knowledgeable of what is good and what is evil, and that he be sure that his denouncement will not lead to a greater evil, and that he knows or believes that his denouncement will remove the evil.

The mother's anger does not prevent the obligation of denouncing evil, provided three conditions are met: the obligation of denouncing is established, the obligation is individual, and the harm resulting from not denouncing is greater than the harm of the mother's anger.

If the change is obligatory, it is not considered disobedience, because filial piety is conditioned by obedience to Allah, along with the necessity of adhering to the manners of discourse with the mother. However, if the one committing the evil is one of the parents, then it has special rulings.