Answer:
a) 早 -> 古 -> 呈 -> 珠
早 SOU, SA, haya(i) , haya(meru) - early, fast, hasten
古 KO, furu(i) - old
呈 TEI - offer, present, exhibit
珠 SHU - pearl
b) 晩 -> 勉 -> 加 -> 嘱
晩 BAN - evening, night
勉 BEN - effort, hard work
加 KA, kuwa(eru), kuwa(waru) - add, append, join, take part
嘱 SHOKU - request, entrust, commission