I don't understand the fascination some people have for paying off the mortgage. Especially since your income has been severely hit.
Running out of liquidity is a nasty thing to have happen to you. And that's just what can happen to people who pay off their mortgage with a big chunk of their cash. OTOH, a 77K balance is pretty small--but I still wouldn't pay it off.
FWIW, I've been retired for 4 years, and just closed on a 4% 30 year refi. My wife let it slip to our neighbors (also retired, but they paid off their house) that we'd just refi'ed and what our payment was. She gasped when she heard our payment amount. But the loan is at 4%, and we have a "preferred & dividend stock" portfolio that earns about 7% and the total portfolio value is about 30% less than the mortgage balance. So we're making net 3% overall and the (lumpy) dividend payout is just a tad smaller than the mortgage payment.