Tabs with ViewPager in Fragment aren't working

Question

Here, I'm going to create a layout of this type

I have done with the NavigationDrawer here with custom ActionBar. And now I need to add Tabs with ViewPager in the first Fragment of the NavigationDrawer. I have done this with the FragmentActivity but when I try same thing with the Fragment I get error of NullpointerException in the navigationDrawerActivity.

First fragment of NavigationDrawer where I need Tabs and ViewPager

public class HomeFragment extends Fragment
    implements OnTabChangeListener, OnPageChangeListener
    {
HorizontalScrollView horizontalSV;
HomeFragmentAdapter uAdapter;
private ViewPager mViewPager;
private FragmentTabHost mTabHost;
private FragmentActivity myContext;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_home, container, false);
    return rootView;
}


@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    mViewPager = (ViewPager) getView().findViewById(R.id.viewpager);
    horizontalSV = (HorizontalScrollView) getView().findViewById(R.id.horizontal_scrollview);
    // Tab Initialization
    initialiseTabHost();
    uAdapter = new HomeFragmentAdapter(myContext.getSupportFragmentManager());
    Fragment first = new First();
    FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
    transaction.add(R.id.tabcontent, first).commit();
    // Fragments and ViewPager Initialization
    mViewPager.setAdapter(uAdapter);
    mViewPager.setOnPageChangeListener(this);
}

// Manages the Tab changes, synchronizing it with Pages
public void onTabChanged(String tag) {
    int pos = this.mTabHost.getCurrentTab();
    this.mViewPager.setCurrentItem(pos);
    final TabWidget tabWidget = mTabHost.getTabWidget();
    final int screenWidth = getActivity().getWindowManager()
            .getDefaultDisplay()
            .getWidth();
    final int leftX = tabWidget.getChildAt(pos).getLeft();
    int newX = 0;

    newX = leftX + (tabWidget.getChildAt(pos).getWidth() / 2)
            - (screenWidth / 2);
    if (newX < 0) {
        newX = 0;
    }
    horizontalSV.scrollTo(newX, 0);
}

// Manages the Page changes, synchronizing it with Tabs
//  @Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
    int pos = this.mViewPager.getCurrentItem();
    this.mTabHost.setCurrentTab(pos);
}

//   @Override
public void onPageSelected(int arg0) {
}

//   @Override
public void onPageScrollStateChanged(int arg0) {
}

public void setCurrentItem(int item, boolean smoothScroll) {
    mViewPager.setCurrentItem(item, smoothScroll);
}

// Tabs Creation
private void initialiseTabHost(){} {
    mTabHost = (FragmentTabHost) getView().findViewById(android.R.id.tabhost);
    mTabHost.setup();
    RelativeLayout.LayoutParams rllp = new RelativeLayout.LayoutParams(
            ViewGroup.LayoutParams.WRAP_CONTENT,
            ViewGroup.LayoutParams.WRAP_CONTENT);
    rllp.addRule(RelativeLayout.CENTER_IN_PARENT);
    Bundle arg1 = new Bundle();
    arg1.putInt("Arg for Frag1", 1);
    mTabHost.addTab(mTabHost.newTabSpec("Tab1").setIndicator("Frag Tab1"),
            First.class, arg1);

    Bundle arg2 = new Bundle();
    arg2.putInt("Arg for Frag2", 2);
    mTabHost.addTab(mTabHost.newTabSpec("Tab2").setIndicator("Frag Tab2"),
            Second.class, arg2);
    mTabHost.setOnTabChangedListener(this);
}

}

And Xml class of it is as:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">


<TabHost
    android:id="@android:id/tabhost"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical">

        <HorizontalScrollView
            android:id="@+id/horizontal_scrollview"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fillViewport="true"
            android:scrollbars="none">

            <TabWidget
                android:id="@android:id/tabs"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:tabStripEnabled="true" />
        </HorizontalScrollView>

        <FrameLayout
            android:id="@+id/tabcontent"
            android:layout_width="fill_parent"
            android:layout_height="0dp"
            android:layout_weight="0" />

        <android.support.v4.view.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom" />
    </LinearLayout>
</TabHost>


</LinearLayout>

Fragment Class is:

public class HomeFragmentAdapter extends FragmentPagerAdapter {
public HomeFragmentAdapter(FragmentManager fm) {
    super(fm);
}

@Override
public Fragment getItem(int index) {
    switch (index) {
        /*    case 0:
                return new First();
            case 1:
                return new Second();*/
    }
    return null;
}

@Override
public int getCount() {
    return 3;
}
}

Thanks.