Honey, people are tired. They are just freakin' sick and tired of hearing and seeing what we all see and hear on every news channel every minute of the day. It's becoming almost like Chinese water torture, you know? The incessant drip, drip, drip.....
Your friend was most likely just having a moment where she felt overwhelmed - and the "good old days" seemed like a nice warm memory to slip in to. We all know the truth tho - each decade had its own scary moments. A 24/7 news cycle only ramps it up to ridiculous levels. Just let her rant for a bit.....we all need to do it now and then.

Say nothing and send her a smile . It does not matter . She was probably not in a good moment , and when not in good place we often think of the past as “ it was the best “.

If I were you, I would probably just let it slide. A lot of folks who aren't very astute politically, are feeling rather confused and burned out these days. They want to return to a time that seemed much simplier and less intense. As long as there's no hate in what she said, may as well let her express what she's feeling. Perhaps you could also make her feel a wee bit better by expressing the hope that better days may be ahead for all of us now that things appear to be heading in a somewhat different direction.
Anyway, that my humble take on it. All the best my friend.

I wouldn't read to much into it. We all say things without thinking through all the ramifications. There is a difference between a flight of fond memory and wishing that the people who suffered in those times should be forgotten. Nobody at the renaissance fair wants the black plague or thinks we should strike the hands off thieves.

Help her in a loving, constructive manner.

"Going back to the good old days of the 1950's" is racist and sexist.

She wants to ban abortions, birth control, civil rights and gay marriage? Keep women barefoot and pregnant?

Does she want to cancel the Civil Rights Act, voting rights for black women, Title IX prohibiting discrimination in education and athletic activities, women's rights, the Americans with Disabilities Act, the Environmental Protection Agency, and allow horrendous air and water pollution again?