How to C# script a 2d top-down NPC's Animation

So I made a Player and a Non Player Character. I wrote a script so the NPC will find the shortest path and follow the Player from a certain distance. It will also stop when the NPC touches the Player. Based on my NPC script, how do I input the animation when the NPC is moving along the X and Y axis. I only have Top,Down,Left,Right animations for the NPC.

Here is my NPC AI script

 using UnityEngine;
 using System.Collections;
 
 public class followingAI : MonoBehaviour 
 {
     
     Transform target;
     public float speed;
     private float minDistance = 1;
     private float maxDistance = 5;
     private float range;
     
     void Update ()
     {
         target = GameObject.FindGameObjectWithTag ("Player").transform;
         
         range = Vector2.Distance(transform.position, target.position);
         
         if (range <= maxDistance)
         {    
             transform.position = Vector2.MoveTowards(transform.position, target.position, speed * Time.deltaTime);        
         }
         if (range <= minDistance)
         {
             speed = 0;
             Destroy (gameObject, 5);
         }
     }
 }

Also here is my first attempt but it failed terribly :(

 using UnityEngine;
 using System.Collections;
 
 public class enemyMovements : MonoBehaviour
 {
 
     private Animator _animator;
     private Rigidbody2D _rigidbody2D;
 
 
     void start ()
     {
         _animator = GetComponent <Animator> ();
         _rigidbody2D = GetComponent <Rigidbody2D> ();
     }
 
 
 
 
     void update ()
     {
 
         CheckDirection ();
 
     }
 
     void CheckDirection ()
     {
         float dirX = _animator.GetFloat ("eVelX");
         float dirY = _animator.GetFloat ("eVelY");
 
 
         if (dirX * rigidbody2D.velocity.x <= 0 ) 
         {
             WalkAnimation (-1, 0);    
         } 
         else if (dirX * rigidbody2D.velocity.x >= 0 )
         {
             WalkAnimation (1, 0);
         }
         else if (dirY * rigidbody2D.velocity.y >= 0 )
         {
             WalkAnimation (0, 1);
         }
         else (dirY * rigidbody2D.velocity.y <= 0 )
         {
             WalkAnimation (0, -1);
         }
 
     
     }
     
     void FixedUpdate ()
     {
         Move ();
     }
     
     void Move ()
     {
         float dirX = _animator.GetFloat ("eVelX");
         float dirY = _animator.GetFloat ("eVelY");
     }
     
     void WalkAnimation (float x, float y)
     {
         _animator.SetFloat ("eVelX", x);
         _animator.SetFloat ("eVelY", y);
         
     }
 }