Step 1: D is mother of J and L.
J is brother of F. So F is also child of D (since J and F are siblings). But F is son of K. So K is the other parent of F. D and K are spouses.
Step 2: K has only three children. Those children are J, L, and F (since D is mother of J and L, and F is also child of D and K).
Step 3: Y is son-in-law of D. Son-in-law means Y is married to D's daughter. D's daughters are L (since J and F are male? J is brother of F, so J is male. L could be femal(e). So L is D's daughter, and Y is married to L.
Step 4: M is son of Y. So M is child of Y and L.
M is brother of S, so S is also child of Y and L.
Step 5: D is mother of L. L is mother of M. So D is grandmother of M.
Step 6: Final Answer: Grandmother.