$(document).ready(function() {
  $('.repeater').repeater({
    repeaters: [{
      selector: '.inner-repeater'
    }]
  });
  $("[data-repeater-list]").on("change", "[name*=cqualificationtxtt]", function() {
    $(this).closest("div")
      .find("[name*=otherqualification]")
      .toggle(this.value==="others");
  })
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery.repeater/1.2.1/jquery.repeater.min.js"></script>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.0.0/dist/css/bootstrap.min.css" />
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.0.0/dist/js/bootstrap.min.js"></script>


<div class="repeater wd_100">
  <div data-repeater-list="data">
    <div data-repeater-item class="o_h mb_15">
      <div class="wd_12 fl_lf  mb_33">
        <label for="applicant_name" class="control-label lbl_hide"><b>Qualification</b>:</label>
        <select class="form-control" data-role="select-dropdown" name="cqualificationtxtt" >
          <option selected="">Select</option>
          <option value="b.tech">b.tech</option>
          <option value="mca">mca</option>
          <option value="others">Others</option>
        </select>
        <input type="text" name="otherqualification" placeholder="Enter Qualification" style="display:none" />
      </div>
      <div class="wd_12 fl_lf mb_33">
        <label for="applicant_name" class="control-label lbl_hide"><b>college</b>:</label>
        <input type="text" class="form-control" placeholder="" name="collagetxt">
      </div>
    </div>
  </div>
  <input data-repeater-create type="button" class="btn btn-success" value="Add" />
</div>