(B) is the answer. We have to check the compatibility of the tenses.
This is a simple sentence given in the question form.
A) "Who you said was coming to see us this evening?" - "you said " is past tense and "was coming" is past progressive tense. so, (A) is wrong here.
C)"Who did you say that was coming to see us this evening?" - "Who" refers to the subject(He/She) and "that" refers to the object. so, (C) is wrong here.
D)""Who had you said was coming to see us this evening?"- "was coming" is past progressive tense and "had you said" is past perfect tense.so,(D) is wrong here.