Deriving PU / PD given a sketch of a PMOS
PMOS is equivalent to fitting a Not Gate on every input. 

I reached this by making the truth table and simplifying, the main differences in your equations look to be from missing the simplification with B*C. when they are both true, you do not care about A.

NMOS = AB+BC



PMOS = A'*B'+B'*C'