Your question is incomplete. What sort of complecations does durg A , drug B   have.

If the person loses conciousness and would have to be live without any sense and need help by people all the time then I don't think drug A should be the answer.

Same with durg B. Asks for possible effects with doctor like wether he/she can walk, have sense and so forth.

If both the above cases are true then you should go for drug C. I know it is hard to make such decision but at least it is honest effort to save his life.