Hi, you are probably describing dementia. Detailed evaluation, examination and some blood tests and MRI brain needed to rule out reversible causes of dementia. Medications can delay the disease progression and relatives can handle her better.
Next Steps
Kindly meet a psychiatrist or a neurologist immediately for detailed evaluation.
Health Tips
Meanwhile as a caregiver, kindly try to keep a fixed routine for her. Don't confuse her with new things. Her long term memory is going to be better than her short term memory which means she will remember old things and not new things. Remind her the date, day, year and time at least 4 times in a day. When you give her tea you may say, it's 8 am and it's tea time and have your tea. Get back if further doubts.
Regards
Dr. Priyadarshani Jain