In a certain code language,
'A + B' means 'A is the mother of B',
'A - B' means 'A is the brother of B',
'A × B' means 'A is the wife of B' and
'A ÷ B' means 'A is the father of B'.
Based on the above, how is K related to N if 'K×L÷M+N-O'?

Expression: 'K × L ÷ M + N - O'?

According to the given information, Family tree diagram of the given expression will be:

As per the arrangements, K is the Mother's mother of N.

Thus, the correct option is (b) Mother's mother.