That seems like a stretch of a conclusion to jump to considering the little information posted.
There are only about 200,000 cases in the US every year.
Encephalitis is most commonly caused by a viral or bacterial infection that directly affects the brain. It can also be caused by a dormant virus that caused infection in the past and becomes reactivated. Common viruses that cause encephalitis are herpes simplex type 1, flu, chicken pox, and West Nile.
A third, more rare, cause is an autoimmune reaction that is triggered by a vaccine. One peer reviewed article I read said there were 1396 cases of encephalitis reported after vaccination in the US from 1990-2010. That's only 70 cases per year.
People who have weakened immune systems are most at risk for encephalitis, so it disproportionately affects the very young and the elderly.
So, while it's not impossible one or more of the vaccines caused the problem, it's very rare and certainly not a conclusion that could or should be drawn just based on the OP. It's also possible the person could have already had a viral infection (pre-vaccination) that caused the encephalitis.
