If you are following mvvm pattern and creating your datagrid in xaml, then you can create a style, which will apply to datagrid buttons. Inside that style you can do:
<setter property="ImageSource" value="{Binding ImageSource}" />
After that in your can set your image:
ImageSource = new BitmapImage(new Uri("..\Images\Deleteicon.png", UriKind.Relative));
Edit
Or you can try something like this :
<DataGrid ItemsSource="{Binding Customers}" AutoGenerateColumns="False" >
<DataGrid.Columns>
<DataGridTemplateColumn Header="Image" Width="SizeToCells" IsReadOnly="True">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button ImageSource="{Binding Image}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
Edit2
In general you should create a style in xaml, with target type button. And then you could find it by code with FindResource() method, after you get the style, you could appily to your datagrid dynamically.
Or you can create style in code behind like
here