The correct option is
B did she
The question tag is a grammatical structure used to convert a
declarative sentence into an interrogative. They are formed using the
auxiliary or modal verb from the statement and the appropriate subject.
When
the statement is negative, the question tag formed is positive. The
same way, for positive statements we use negative question tags.
Option B: In the given statement, the auxiliary verb used is 'didn't' (did
not), the subject is 'she'. The sentence is negative, hence the
correct tag will be positive.
So, the question tag formed is: did + she
Hence option B is correct.
Options
A and C: 'Wasn't she' and 'didn't she' are negative question tags and do
not agree to the sentence. Hence they are incorrect.
Option D: 'Was she' consists of the auxiliary verb 'was'.
The question tag is formed with the independent clause (She didn't...), as opposed to the dependent clause (where his wife was).
The
verb 'was' is in the dependent clause (where his wife was), hence we
cannot form a question tag with it, and D is incorrect.