Is it considered disobedience for a girl to be preoccupied with her studies instead of helping her mother with household chores, if the mother asks her to focus on her studies, but the girl feels guilty about the little help she provides?

It is best to combine studying lessons with helping the mother with household chores. If combining them is difficult, the daughter should respond to her mother's request to focus on her studies while helping her in ways that do not hinder her, because obeying one's mother in what is good is obligatory.