OP states
‘she is now legally allowed to drive’
and
‘She wasn’t legally required to surrender her license’
i know from personal experience, and the DVLA website confirms this, that you MUST surrender you licence if you have epilepsy. If you don’t, you could be fined £1,000, even if you don’t drive.
if you want to drive again, you then have to re-apply for your licence and the DVLA will do their investigations on a persons health and they then may be allowed to have their licence back.
so although OP’s mother didn’t drive for 2 years, and has had no epileptic episodes for over a year, that doesn’t mean she can just get back in a car and drive again. Her licence wouldn’t be valid as the DVLA have not approved her to drive.
if this affects you, please double check by phoning the DVLA - they are very helpful.
From the DVLA website:
Epilepsy and driving
You must tell DVLA if you've had any epileptic seizures or blackouts.
You must stop driving straight away.
You can be fined up to £1,000 if you do not tell DVLA about a medical condition that affects your driving.
You may be prosecuted if you're involved in an accident as a result.
DVLAwill let you know whether or not you qualify after you’ve filled in the form. Until you hear from them you must stop driving.