You have been called by family members for their mother who is "not acting right." On scene the family informs you that they are concerned because their 68-year-old mother has been complaining of a headache and today is very confused. Assessment reveals a bruise to the right side of the head that family states occurred one week ago when she fell in church. Since all other aspects of the assessment are normal, you suspect a head injury. Which condition would make the most sense given these findings and history?