Seizure- keppra medication

My mom had her first seizure probably around 6 years ago. Since then she never took any seizure medication because her seizure were not very frequent ( maybe once every 5-8 months or less). Around 3 months ago she had a seizure at work which prompt her to visit a neurologist. The doctor prescribed her keppra 500 mg a day and its been around a month since she started. She was recently diagnosed with breast cancer so I believe that the combination of her diagnosis along with the side effects of keppra are making her very depressed, angry and easily agitated. I also read that keprra can be damaging to the kidney and unfortunately my mom was born with only 1 kidney. So do you think she should stay on keppra even when her seizures are infrequent? Do you think the benefit of keprra outweighs the negative changes in behavior and kidney damage the drug may cause?

Thank you

Sincerely,
A concerned daugther