- Shall we ask him to come early?
A. That's really not necessary.
B. Any time at all.
C. Yes, we shall.
Should I answer the C because of the question start with shall? Or it is wrong. Please guide me.
You should recognise this as not being a true "question", but a "suggestion" (phrased as a question). The speaker is not asking if something is true or false, but offering an idea and asking for your comment.
All are grammatically correct. But B is a non-sequitur. It doesn't respond to the suggestion. C is an answer to a question, but we aren't being asked what shall happen, but asked for an opinion on the suggestion.
A is the only answer that responds appropriately to the suggestion.