as far as I know, aphasia comes with a stroke to the left
hemisphere in the area called Broca's area.

Was his fall a stroke? Do you know?

Males have all the language forming parts of the brain on the left.
Females have that left side predominance but also some right sided language ability.

My husband's grandfather had a stroke and was permanently aphasic the rest of his life. (he lived about 10 yrs after that, and was very frustrated since the therapy did not work).
Today they are much better with this, so there is hope still.

So sorry this has happened.