If A is the mother of P and Q. B is the husband of A.  C is the son of B’s brother. What is the relation of A with C?

Aunt

↑ or ↓ ⇒ Upward or downward line shown "generation gap" .

   =    ⇒ Double lines shown "relation b/w Husband & Wife"

   —   ⇒ single line shown "relation between them other than Husband & Wife".

P and Q are the children of A (mother) and A and B are couple. B’s brother is not given but Son (C) is related with Aunt.

So, option (3) Aunt is correct.