Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/16
Q:1/4=90
M:6/8
K:Eb
['c2 B4 B B']  
X:1
L:1/16
Q:1/4=90
M:6/8
K:Eb
 G4 G2 G2 F2 B,2 | B12 | G4 G2 G2 F2 B,2 | (B6 B2) B2 c2 | d3 d d2 c4 c c | B2 B B2 d4 d d | 
 d2 c2 B2 f4 c c | B2 B2 c2 B4 B B | e3 e e2 d4 d d | c3 c c2 B4 B B | e3 e e2 d4 d d | 
 c3 c c2 B4 B B | c3 c c2 B4 B B | A3 A A2 G4 =A2 | B4 B2 c4 d2 | e4 e2 f4 B2 | _d4 d2 c3 B A2 | 
 B6 B6 |]  