How to bring a character's hand to a given position (IK) C#

I want to make a Big Monster that spots the player last position and at that last position Monster Hit his Hand at that players last know position.

I created states and found the player position please tell me so that i can bring monster hand to that player position where my player was.C#

public enum State { Idle, Attack, Investigate }

 //public GameObject target;

 public State state;
 private bool alive;

 Transform playerTransform;

 // Variables for Investigate



 // Variable for Idle



 // Variable for Attack

 // Use this for initialization
 void Start ()
 {
     state = EBasicAI.State.Investigate;

     alive = true;

     StartCoroutine("FSM");
 }
 
 // Update is called once per frame
 void Update () {
     
 }

 IEnumerator FSM()
 {
     while (alive)
     {
         switch (state)
         {
             case State.Investigate:
                 Investigate();
                 break;
             case State.Attack:
                 Attack();
                 break;
         }
         yield return null;
     }
 }

 void Investigate()
 {
     Debug.Log("Investigate");
 }

 void Attack()
 {
     Debug.Log("Attacking");
     GetPlayerTransform();
     //target = GameObject.FindWithTag("Player").transform;
 }

 void GetPlayerTransform()
 {
     GameObject go = GameObject.FindWithTag("Player");
     if (go != null)
     {
         playerTransform = go.transform;
         Debug.Log("player found");
         //transform.LookAt(playerTransform);
     }
     else
     {
         Debug.Log("player not found");
     }
 }


     void OnTriggerEnter(Collider coll)
 {
     if (coll.tag == "Player")
     {
         state = EBasicAI.State.Attack;
         //target = coll.gameObject;
     }
     //else
     //{
        // state = EBasicAI.State.Investigate;
    // }
 }

 void OnTriggerExit(Collider coll)
 {
     if(coll.tag == "Player")
     {
         state = EBasicAI.State.Investigate;
     }
 }