The answer depends on why she was prescribed the anti-epileptic medication.
If it was to temporally prevent her from having seizures which was secondary to an illness other than epilepsy
, then she can be weaned of the medications with a doctor's follow-up. However if it was prescribed because she developed epilepsy, then she will need to take it for a lifetime except she develops side-effects for which the medication will need to be changed to another one she can tolerate better.
There are many anti-seizure medication and if she is developing side effects with Keppra
, it is advisable to see the physician who prescribed it and complain so that it can be changed and she put on medication she can tolerate.
It is true to wean someone off such drugs, the dose has to be reduced progressively before being stopped but you will need to see the physician who prescribed it and ask if she can be weaned off it before she gradually stops taking it. If the doctor still wants her to be on an anti-seizure medication, then you can ask if she can be put on one she can tolerate and with less side-effects.
Good luck, quick recovery & say hi to her (your mum). :-)