avoid creating empty row in datagrid

I think your datagrid's CanUserAddRows property is set to true. Just set it to false to fix your issue.

CanUserAddRows="false"
IsReadOnly="True"

EDIT : Sorry. I read your question properly right now. It’s because the ObservableCollection’s type is object. I will show you a small sample so that you understand how binding works in a datagrid. Your collection should have public properties, so datagrid could bind columns to it. If you use collection type of Object than you have no properies for binding, so the empty rows will be displayed.

XAML :.

<DataGrid AutoGenerateColumns="False" Height="253" HorizontalAlignment="Left" Margin="27,24,0,0" Name="dataGrid1" VerticalAlignment="Top" Width="448">
            <DataGrid.Columns>
                <DataGridTextColumn Header="First" Binding="{Binding Path=Field, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
            </DataGrid.Columns>
 </DataGrid>

Code behind :

public partial class MainWindow : Window 
{ 
    public ObservableCollection dataSource;
    public MainWindow()
    {
        InitializeComponent();

        this.dataSource = new ObservableCollection<SomeDataSource>();

        this.dataSource.Add(new SomeDataSource { Field = "123" });
        this.dataSource.Add(new SomeDataSource { Field = "1234" });
        this.dataSource.Add(new SomeDataSource { Field = "12345" });

        this.dataGrid1.ItemsSource = this.dataSource;
    }
}

public class SomeDataSource
{
    public string Field {get;set;}
}