Q:

To place menu component inside the column of the table

I am using table component, In the table component i want to place menubutton in last row like this:
 
Actually i have added the menu button inside 3rd column and gave float:right;, but i want to add this button inside the table by creating another column.How  to do this?

A:

Just add the button inside table. 
On your component declare a new display column named something like actions :
displayedColumns: string[] = [ your_rest_declarations...,'actions'];

Then add this to your view:
    <!-- Actions -->
   <ng-container matColumnDef="actions">
    <th mat-header-cell *matHeaderCellDef> Actions </th>
    <td mat-cell *matCellDef="let element"> 
      <button mat-icon-button >
          <mat-icon aria-label="actions">more_vert</mat-icon>
      </button>
    </td>
  </ng-container>

Result:

