Answer:
They should end up like this. 先+後 走+歩 夢+現 児+老 愁+喜
先 SEN, saki - previous. before
後 GO, ato, nochi - after
走 SOU, hashi(ru) - run
歩 HO, BU, aru(ku), ayu(mu) - walk
夢 MU, yume - dream
現 GEN, arawa(reru), arawa(su) - present, appear, show
児 JI, NI - small child, infant
老 ROU, o(iru), fu(keru) - grow old
愁 SHUU, ure(i), ure(eru) - grief, sorrow, grieve, anxiety
喜 KI, yoroko(bu) - be glad