How can a girl return to her commitment and devotion after being influenced by uninhibited company in her accommodation, and is it advisable to move to separate accommodation despite its high cost?

Being affected negatively or positively by a friend is inevitable. Therefore, Islamic law encourages choosing righteous company. The Prophet, peace and blessings be upon him, said: "The example of a good companion and a bad companion is like that of the perfume seller and the blacksmith." Al-Nawawi interpreted this hadith as "the desirability of associating with righteous people." Your living with the aforementioned girls—given the situation you described—is dangerous. Religion is the most precious possession of a Muslim; if one's religion is lost, that is a clear loss. You can search for an alternative to living with them. You can live alone while continuing your studies, even if it means some hardship. It is also suggested that you look for righteous girls who wish to live away from places of disobedience, so you can cooperate in goodness, in accordance with the Almighty's saying: "And cooperate in righteousness and piety." And do not forget to supplicate frequently for the matter to be eased.