Which number line shows the solution for

It's the last choice.

Step-by-step explanation:

| n | ≤ 2  represents the distance between n and 0 that is less than or equal to 2.  The dots on the 2 and -2 are black because the equal sign is part of the inequality.

Note the vertical lines about the n mean the absolute value of n - the positive distance between  n and 0, which has a maximum of 2 either side of the 0.