Answer:
a) 努 -> 加 -> 員 -> 賦
努 DO, tsuto(meru) - exert self, make efforts, strive
加 KA, kuwa(eru), kuwa(waru) - add, append, join, take part
員 IN - member
賦 FU - tribute, payment, installment
b)婆 -> 如 -> 員 -> 賄
婆 BA - old woman
如 JO, NYO - equal, like, as, as if
員 IN - member
賄 WAI, makana(u) - provide board, supply, furnish