Even if CodeIgniter's distinct() is given a column name, select('*') returns duplicate rows

How can I use Distinct with join in CodeIgniter, I'm trying to fetch customer's name and registered category, but my problem is whiles fetching the data I'm getting data in repetation because of sub-category, I've used distinct but then I'm getting Ambiguous field error, how can I solve this problem.

My View

<table class="table table-hover example1">
<thead>
<tr>
    <th>SNo.</th> 
    <th>Business Name</th>
    <th>Category Name</th>
    <th>Edit</th>
</tr> 
</thead>
<tbody>
 <?php $i=0;
 foreach($value as $row){ ?>
 <tr>
    <td><?php echo ++$i;?></td>
    <td><?php echo $row->Bussiness_Name;?></td>
    <td><?php echo $row->Category_Name;?></td>
    <td onClick="RestoreVendor(<?php echo $row->Business_Id; ?>,<?php echo $row->Trash;?>,'<?php echo $row->Bussiness_Name;?>')" class="btn btn-primary">Remove</td>
 </tr>
 <?php }?>
 </tbody>
 </table>

My Controller:

 public function removecategory()
 {
    $this->load->model('VendorModel');
    $data = $this->VendorModel->remove_category();
    $this->load->view('admin/remove_cat', array('value'=>$data));
 }

My Model

 public function remove_category()
{
    $this->db->select('*');
    $this->db->distinct('Category_Id');
    $this->db->from('business_mapping');
    $this->db->join('business_profile_details', 'business_profile_details.Business_Id = business_mapping.Business_Id');
    $this->db->join('category_master', 'category_master.Category_Id = business_mapping.Category_Id');
    $query = $this->db->get();
    return $query->result();
}

result image

You can use below mentioned query.

$query = $this->db->group_by('category_master.Category_Id,business_profile_details.Business_Id');

Please try above, It will help you.