Answer:
Sheila's mum asked her who she had met the previous night.
Explanation:
There are a few things we need to keep in mind as we report the question.
1. The question is in the simple past tense. When reporting it, we change it to the past perfect tense.
2. The time expression "last night" becomes "the previous night" or "the night before".
3. The question must no longer be structured as a question. Thus, the auxiliary "had" in the past perfect does not come before the subject "she".
4. As mentioned above, the subject is now "she" referring to Sheila. We can no longer use "you" as in the question.
Therefore:
Sheila's mum asked her who she had met the previous night.
