What is the ruling of Islamic law regarding the interaction of a woman, who grew up in the house of her stepmother, with her stepmother's brothers who were like maternal uncles to her, and how should she behave with them and with her stepmother who did not accept her hijab in front of them?

The brothers of your stepmother are not your mahram. Therefore, it is not permissible for them to be in seclusion with you, nor is it permissible for you to uncover your awrah in front of them. Your stepmother must understand this matter and adhere to Islamic law. Allah Almighty says: "And it is not for a believing man or a believing woman, when Allah and His Messenger have decided a matter, that they should have [any] option in their decision." However, if you were nursed by your stepmother five full, satisfying times during the first two years (of your life), then she becomes your foster mother, and her brothers become your maternal uncles (through fosterage).