ok. since this is not a real patient, you want to start by looking at the signs and symptoms of atrial fibrillation and what is going on when a patient has a hip replacement.
the atrial fib isn't too hard. the symptoms are: dyspnea, dizziness, palpitations and fatigue. next, you want to extend that to the possibilities of what kind of help this person would need with their adls (activities of daily living). think
about how the impact of each one of those symptoms is going to have on things like eating, toileting, bathing, mobility, etc. you should have a list of adls to refer to as you do this. that will give you the assessment data for this patient.
do the same with the hip replacement. you need to look at the possible reasons for a hip replacement. some type of arthritis? fracture of the hip? then find the symptoms of each of those medical problems. look beyond a fracture and ask why a fracture might have occurred. is it possible the patient might have an underlying neurological problem causing problems with balance which led to a fall? is there any dementia that might suggest the patient has safety issues and makes wrong judgments to the point of getting into unsafe conditions leading to falls?
this is what you are being asked to do with this kind of exercise. you are being asked to use some creative and critical thinking.
here are some links to information about these conditions: