odoo-survey-addons/survey_custom_matrix/templates/matrix.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>

  <template id="matrix" inherit_id="survey.matrix">
    <xpath expr="//table" position="replace">
      <table class="table table-hover">
        <thead>
          <tr>
            <th></th>
            <th t-foreach="question.labels_ids" t-as="col_label"><span t-field="col_label.value"/></th>
          </tr>
        </thead>
        <tbody>
          <tr t-foreach="question.labels_ids_2" t-as="row_label">
            <th><span t-field="row_label.value"/></th>
            <td t-foreach="question.labels_ids" t-as="col_label">
              <input t-if="question.matrix_subtype == 'simple'" type="radio" t-att-name="'%s_%s' % (prefix, row_label.id)" t-att-value='col_label.id'/>
              <input t-if="question.matrix_subtype == 'multiple'" type="checkbox" t-att-name="'%s_%s_%s' % (prefix, row_label.id, col_label.id)" t-att-value='col_label.id'/>
              <t t-if="question.matrix_subtype == 'custom'">
                <textarea t-if="col_label.type == 'free_text'" class="form-control" rows="3" t-att-name="'%s_%s_%s' % (prefix, row_label.id, col_label.id)"></textarea>
                <input t-if="col_label.type == 'textbox'" type="text" class="form-control" t-att-name="'%s_%s_%s' % (prefix, row_label.id, col_label.id)"/>
                <input t-if="col_label.type == 'numerical_box'" type="number" step="any" class="form-control" t-att-name="'%s_%s_%s' % (prefix, row_label.id, col_label.id)"/>
                <!-- <div t-if="col_label.type == 'date'" class='input-group date' t-attf-id="#datetimepicker_#{question.id}_#{row_label.id}_#{col_label.id}" data-target-input="nearest">
                  <input type="text" class="form-control datetimepicker-input" t-attf-data-target="#datetimepicker_#{question.id}_#{row_label.id}_#{col_label.id}" t-att-name="'%s_%s_%s' % (prefix, row_label.id, col_label.id)"/>
                  <div class="input-group-append" t-attf-data-target="#datetimepicker_#{question.id}_#{row_label.id}_#{col_label.id}" data-toggle="datetimepicker">
                    <div class="input-group-text"><i class="fa fa-calendar"></i></div>
                  </div>
                </div> -->
                <select t-if="col_label.type == 'dropdown'" t-att-name="'%s_%s_%s' % (prefix, row_label.id, col_label.id)" class="form-control" id="seldpbox1">
                  <option></option>
                  <t t-foreach="col_label.value_ids" t-as="dpv">
                    <option t-att-value="dpv.id"><t t-esc="dpv.name"/></option>
                  </t>
                </select>
                <input t-if="col_label.type == 'checkbox'" type="checkbox" t-att-name="'%s_%s_%s' % (prefix, row_label.id, col_label.id)" t-att-value='col_label.id'/>
              </t>
            </td>
          </tr>
        </tbody>
      </table>
    </xpath>
  </template>

</odoo>