Are these sentences both correct:
1-These are the people I want to help most.
2-These are the people I most want to help.
I think "1" can mean the same as "2' but it could also mean: I want to help them more than I help anyone else.
"Best" could modify both "want" or "to help". The sentence is ambiguous, although probably in real life the difference would not be really important.
I would say yes to both questions and assume that best is a typo and should read most.