Quests/Dialogue (C#)

So i want to make a quest. i have a select script and i have a dialogue box. now i need to connect the two so that when a specific object is selected and then you right click the dialogue will pop up. i ran into 1 problems when i was trying to make this script 1. you are pushing more gui clips then you are popping. this is how the scrip looks for the dialogue

 using UnityEngine;
 using System.Collections;
 
 public class Speek : MonoBehaviour {
 
 // Use this for initialization
     
 public void Start ()
 {    
 CurrentMenu = MainMenu;
 DisplayMenu = false;
         Dad = false;
 }

 public void Update()
 {    
 if (Input.GetMouseButtonDown(1))
     DisplayMenu = !DisplayMenu;
     if (Input.GetKeyDown("q")){
         Dad = true;
     }
 }
 
 public void OnGUI()
 {
 if (DisplayMenu)
             
 CurrentMenu();
 if(Dad)
    dad();        
 }
 
 private delegate void MenuDelegate();
 
 private MenuDelegate CurrentMenu;
 private bool DisplayMenu;
 public bool Dad;
     
 public string nameOfGiver;
 public string nameOfDone;
 public string QuestPage1;
 public string QuestPage2;
 public string Answer;
 private bool Quest = false;
 private bool DadDone = false;

 //
 // Main menu
 //
 private void MainMenu ()
 {
 Rect MainMenuRect = new Rect((Screen.width - 280) / 2, (Screen.height - 100) / 1.03f, 630, 108);
 GUI.BeginGroup(MainMenuRect);
 GUI.Box(new Rect(10, 10, MainMenuRect.width, MainMenuRect.height),  nameOfGiver );
         GUI.Label(new Rect(25, 25, 540, 80), QuestPage1 ); 

 if (GUI.Button(new Rect(540, 80, 80, 20), "Next"))
 {   
 CurrentMenu = Next;
 }
 }
     
 private void Next(){
 Rect OptionsRect = new Rect((Screen.width - 280) / 2, (Screen.height - 100) / 1.03f, 630, 108);
 GUI.BeginGroup(OptionsRect);
 GUI.Box(new Rect(10,10,OptionsRect.width,OptionsRect.height), nameOfGiver );
 GUI.Label(new Rect(25, 25, 540, 80), QuestPage2 );
         
 if (GUI.Button(new Rect(15, 80, 80, 20), "Back"))
 {
 CurrentMenu = MainMenu;
 }
 
 if (GUI.Button(new Rect(540, 80, 80, 20), "Okay"))
 {
 DisplayMenu = false;
 }
 }
             
 private void dad(){
 Rect OptionsRect = new Rect((Screen.width - 280) / 2, (Screen.height - 100) / 1.03f, 630, 108);
 GUI.BeginGroup(OptionsRect);
 GUI.Box(new Rect(10,10,OptionsRect.width,OptionsRect.height), nameOfGiver );
         GUI.Label(new Rect(25, 25, 540, 80), Answer );    
 
 if (GUI.Button(new Rect(15, 80, 80, 20), "Back"))
 {
 CurrentMenu = MainMenu;
 }

 if (GUI.Button(new Rect(540, 80, 80, 20), "Okay"))
 {
 DisplayMenu = false;
 Quest = true;
 }                
 }
     
     
     }

}
}
}

and this is how the targeting script looks like

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class TargettingQuest : MonoBehaviour {
     public List<Transform> targets;
     public Transform selectedTarget;
     public GameObject target;
      
     
     private Transform myTransform;
         
     // Use this for initialization
     void Start () {
         targets = new List<Transform>();
         selectedTarget = null;
         myTransform = transform;
         
         AddAllEnemies();
     }
     
     public void AddAllEnemies() {
         GameObject[] go = GameObject.FindGameObjectsWithTag("Enemy");
         
         foreach(GameObject enemy in go)
             AddTarget(enemy.transform);
     }
     
     public void AddTarget(Transform enemy) {
         targets.Add(enemy);
     }
     
     private void SortTargetsByDistance() {
         targets.Sort(delegate(Transform t1, Transform t2) {
                 return Vector3.Distance(t1.position, myTransform.position).CompareTo(Vector3.Distance(t2.position, myTransform.position));
                 });
     }

     #region
     //This is added by adrian 
     #endregion

     //if we do not have an enemy targeted ywt, then find the clostest one and target him
     //if we do have an enemy targeted, then get the next target
     //if we have the last target in the list, then get then first target in the list
     private void TargetEnemy() {
         if(selectedTarget == null) {
             SortTargetsByDistance();
             selectedTarget = targets[0];
         }
         else {
             int index = targets.IndexOf(selectedTarget);
             
             if(index < targets.Count - 1) {
                 index++;
             }
             else {
                 index = 0;
             }
             DeselectTarget();
             selectedTarget = targets[index];
         }
         SelectTarget();
     }
     private void SelectTarget() {
         selectedTarget.renderer.material.color = Color.red;
 }

     private void DeselectTarget() {
         selectedTarget.renderer.material.color = Color.white;
         selectedTarget = null;
     }
     
     // Update is called once per frame
     void Update () {
         if(Input.GetKeyDown(KeyCode.Tab)) {
             TargetEnemy();
         }
         float distance = Vector3.Distance(target.transform.position, transform.position);
         
         Vector3 dir = (target.transform.position - transform.position).normalized;
         
         float direction = Vector3.Dot(dir, transform.forward);
         if(distance < 2.5f) {
             if(direction > 0) {
             Speek pa = (Speek)GetComponent("Speek");
         pa.Dad = true;
     }
 }
 }
 }

How can i set the distance so i cant select the object when it more then 1 yrd away from me?

how can i make it so when i press okay the quest begins .. ( in this case the quest asks you to go talk to your dad. so i want it to be that if you talk to your dad before you get the quest noting should happen and then when you press okay another script activates that lets you to clame your reward.