盡快回去。不要等到最後。人活著時的陪伴，對家人很重要。
工作請假請看以下政府 fact Sheet. Under Family Medical Leave Act, if you meet the requirement, you are entitled to have up to 12 weeks unpaid leave to care for a family member for serious illness. Human Resources will not give you problem. it is the law. You need a doctor's note for your mother stating her illness. hope this helps.
https://www.dol.gov/whd/regs/compliance/whdfs28.pdf
