Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned by the swelling on the face of your mom 2 months after brain surgery for CSF rhinorrhea.
After brain surgery, swelling of the face or head is common and head end of the bed is kept raised to reduce the swelling. But it's been two months since your mom underwent brain surgery and quite unlikely for the swelling to develop so late after surgery.
Other reasons for the facial swelling like drug reactions, allergic reactions,angioedema, cellulitis also need consideration. You must consult your physician for definitive diagnosis as the same is not possible online.
Hope this helps. Take care.
Note: This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.