How To Treat Seizures Caused Post Brain Tumor Surgery?

im asking this question cause my hasnt got a computor....my friend had a brain tumor removed in aug 2014 ...in nov 2014 had a seizeure...the drs put her on dilanton 100mg 4x a day...she went on mon had blood test done and they called the next day and told to take only 3 day cause her count was 102...should be betwen 40-80...now she is afraid she mite have another seizure if she goes less with the meds....she wants to know if she will have another seizure or not...i told her as long as she on the meds she was 95% safe cause only god knows ...is this rite? tks