The correct option is B Would
Here, 'would' is correct as it is used to ask someone politely for something. Here, someone is asking someone politely that he might like to have some tea.
'Will' is incorrect here as it is used for showing that somebody is willing to do something or is used for asking somebody to do something. Example: Will you do this work for me.
'Are' is used with a plural noun or pronoun. Example: Are they coming to the function.
'Can' is used to say that it is possible for somebody/something to do something, or for something to happen. Example: Can you come back tomorrow?