That's such a tragic situation buddy. I've heard a lot of stories about people not being able to get their families into the United States legally over the years. As much as I complain about other countries being dicks about their visas, the US is much much more difficult.
What about Mexico? I've heard stories about how they will let basically anyone in there.
Many 'Mericans that live in Mexico don't fool with residency because I think you can stay 180 days per year without a visa, but Cambodians need a transit visa to even use Mexican airports, it was a problem for us on the way to Ecuador, had to avoid Mexican and USA airports.
Before heading to Asia many years ago I looked into Mexican residency visas, and it was tough. They required at least on year history of depositing $2,000 USD+ into an American bank account and to have earned at least that much in salary for a year before attempting to get the visa from the Mexican Embassy in the USA.
Most of the people that actually buy homes and do the retirement thing usually earn far more than that, so it's not a problem, but I never even earned more than $1,500 per month in the USA while working 60 hours a week.
Panama is the most open visa-wise, but I've never been interested in living or visiting there, plus it's expensive to go through the process, lawyers required for every document, everything apostilled from the USA, etc.