Is there any sin upon a woman who continues to receive treatment from her father's company's housing fund after her marriage, knowing that her right to treatment expires upon marriage?

There is no objection to subscribing to and benefiting from cooperative funds if they are governed by Sharia (definition)-compliant regulations. Adherence to the subscription terms is obligatory, and it is not permissible to resort to deception to benefit from them. This is based on the Prophet's (peace and blessings be upon him) sayings: "Muslims are bound by their conditions, as long as they conform to the truth," and "Whoever deceives is not of us." Therefore, it is not permissible for you to receive treatment at the fund's expense after marriage, and you must repent and return what you have unduly benefited from.