Accessing a prefab after instantiating results as null

I am instantiating a prefab from resources folder, after that when I try to access it through GetComponent, it returns as null and throws me the below error:

NullReferenceException: Object reference not set to an instance of an object dreamBathHomeScreen.AfterCategoryProcessingComplete () (at Assets/DreambathScripts/dreamBathHomeScreen.cs:188) dreamBathHomeScreen+c__Iterator1.MoveNext () (at Assets/DreambathScripts/dreamBathHomeScreen.cs:173) UnityEngine.SetupCoroutine.InvokeMoveNext (IEnumerator enumerator, IntPtr returnValueAddress) (at C:/buildslave/unity/build/Runtime/Export/Coroutines.cs:17)

Here is my code:

 void AfterCategoryProcessingComplete ()
 {
     productCategoryScreen.SetActive (true);

     foreach (dreambathHomeCategories c in homeCategoriesList) {
         GameObject button = Instantiate (Resources.Load ("dreamBath/horizontalCategories"), verticalScrollCategoryContent.transform) as GameObject;
         button.transform.GetChild (0).gameObject.GetComponent<Text> ().text = c.CategoryName;
         Debug.Log (c.CategoryName + "----------");
         foreach (dreambathHomeCategories d in c.subcategory) {
             GameObject parentS = button.GetComponent<horizonalCatPopulate> ().contentScroll;
             GameObject buttonCh = Instantiate (Resources.Load ("dreamBath/subCategoryBtn"), parentS.transform) as GameObject;
             Debug.Log (d.CategoryName + d.CategoryId + "----------");
             buttonCh.GetComponent<subCatBtnPopulate> ().Instancename (d); //ERROR ON THIS LINE
         }
     }

     foreach (dreambathHomeCategories c in homeCategoryImgUrl) {
         Debug.Log (c.homecatImg + "----------");
         ImageProcessing (c.homecatImg, imgHomeCategory);
     }
         
 }