My friend is losing her home of over 25years due to social security's mistake-how nasty can it get

[haele]

34. Oof, Washington - No income taxes and everything is paid through Property and Sales taxes

It sounds like with SSI pulling the additional money, she won't be able to pay up during any grace period the state may give her, and will fall behind even further for the next couple years. Three years of non or partial payments, and they take you to court.
And yeah, there's some property tax exemption for old age - or poverty - on primary residences in Washington State. They'll work with you, but only so much. If your income is being garnished - by the State or the Feds, that is not an excuse for not paying what the State has assessed you to pay.
Even if she sells, she won't end up with enough after the sales tax plus her back property tax to get a smaller place to live, unless she did what my folks did when they retired and the property tax started cutting into their savings; they sold their Ravenna Park house of 35 years and moved to Albuquerque where they could afford to be comfortable in their old age.