That would still mean that a single country, albeit the largest one turns 1.56% of it's population into homeless each year. Looking at statistics for California as a whole there's no room to account for those homeless people so it doesn't look like they are being dumped beyond the county lines.

So either they all died which would greatly skew the population statistics in the US as a whole, moved out of California (which doesn't seem to be the case since homelessness in adjutant states didn't sky rocket) or the truth is more closer to what was stated than to yours.

(I would concede that perhaps that they might be in Mexico if you really want to explore this further)

Also 9 million residents received "public assistance"? Even if it's over 8 years it's still a huge number considering that the LA county has a population of about 10M, so unless going to school, voting, going to a hospital or being borne counts as "public assistance" I would really like to see exactly how they got to that number since the immigration statistics for that country cannot account for a transfer of so many residents to have 9M requiring actual "public assistance" over any reasonable period of time yet alone 8 years...