Q= S1·S0'·A'·B' + S1'·S0'·A + S1·S0·B + S1'·S0'·B + A·B



First term:

truth table (S1 and not(S0) and not(A) and not(B))


Two terms:

truth table (S1 and not(S0) and not(A) and not(B)) or
 (not(S1) and not(S0) and A) 

Complete SoP:
truth table (S1 and not(S0) and not(A) and not(B)) or
 (not(S1) and not(S0) and A) or (S1 and S0 and B) or
 (not(S1) and not(S0) and B) or (A and B)