Given the increased chances of someone who's nearly 80 of needing medical help on a trip, and the epic size of bills over in the states, I'm not surprised you're struggling to find decent priced coverage...

I'd be tempted to try someone like Saga for a quote, they specialise in older people, and are apparently pretty good about being able to cover pre-existing conditions too. See https://www.saga.co.uk/insurance/tra...urance/over-70

Otherwise, it is possible to buy US Health Insurance for people on short trips. That won't help with repatriation costs though, so an ER visit and a stay would be (mostly...) covered but airline change fees and/or an accompanying nurse on the delayed flight home wouldn't be. You also have to deal with all the usual problems with US Health Insurance exclusions and billing, with the added fun of being in another country by the time the unexpected bills start showing up! During covid when our travel insurance didn't cover some stuff we ended up buying 2 weeks coverage via https://www.visitorscoverage.com/vis...surance/plans/