My friend, subarachnoid hemorrhage is a hemorrhagic disease caused by subarachnoid hemangioma or vascular disease. The severity of symptoms depends on the location of the lesion and the amount of bleeding, which is related to the age of onset. The main danger lies in sudden massive hemorrhage, leading to acute communicating hydrocephalus and sudden increase of intracranial pressure, leading to the formation of cerebral hernia. Judging from your mother's condition, her condition is mild and stable, and it is estimated that the amount of bleeding will not be much. Do digital subtraction angiography as soon as possible, and make clear the lesion site, prognosis and treatment plan. When you are in the hospital, you can rest assured that it is your task to cooperate with the doctor, and don't think about anything else. May everything be safe.
Personal opinion, for reference only, I hope it will help you.