Would it be correct to say, "Others wouldn't hence their fear" ?
With the comma before hence, it could be correct in a very particular context like this:
'Those days, we would go to the therapist every day. Others wouldn't, hence their fear.'
'Hence' is a word that start an answer to a question beginning with 'whence'. It's a pair like 'what' - 'that', 'when' - 'then', 'where' - 'there'.
'Whence' means 'from where'. You could ask 'whence do you come?' meaning 'where do you come from?' And the answer could be 'hence I come' that means 'I come from here.'
But the word has also an additional meaning. 'Hence' might mean 'for this reason' as well (as in the sentence I gave above). Hope it helps.
I am not a teacher nor a native-speaker.