Concept:"Ought not to" expresses strong advice against doing something.
Explanation:The sentence advises against an action that is risky or unwise.
Walking home alone late at night is dangerous, so the speaker is recommending that the person should not do it.
The phrase that best expresses this advice is "ought not to".
Option A, "would not", suggests refusal or a future action, not advice.
Option B, "might not", indicates possibility, meaning it is possible that the person will not walk.
Option D, "need not to", is grammatically incorrect because the correct form is "need not" without "to", and it expresses lack of necessity, not strong disapproval.
Therefore, the correct choice is option C.
Answer:C. ought not to