Columns are getting repeated in Transformation

The transformation repeats a single row of data. So if your transformation is defining the header row in each row of data, you will end up with what you have now. You need to remove the <table> and <th> definition in your item transformation and place that in the content before and content after properties of the webpart. There are a few other things you could do as well but that by far is the most simple approach.

Content before:

<table class="tablestyle">
    <tbody>
        <tr>
            <th>
                <div style="width: 175px;">Job Work</div>
            </th>
            <th>
                <div style="width: 175px;">1st Responsible</div>
            </th>
            <th>
                <div style="width: 175px;">2nd Responsible</div>
            </th>
            <th>
                <div style="width: 175px;">Escalation</div>
            </th>
        </tr>

Item transformation:

        <tr>
            <td><%# Eval("Job_Work") %></td>
            <td><%# Eval("First_responsible") %></td>
            <td><%# Eval("Second_responsible") %></td>
            <td><%# Eval("Escalation") %></td>
        </tr>

Content after:

    </tbody>
</table>