JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.aspnetcdn.com/ajax/jquery.validate/1.14.0/jquery.validate.js"></script>
<form id="myform" action="submit.php">
  <select name="cause[0]" id="cause" class="cause">
    <option value="">Cause to Support</option>
    <option value="993">Medical</option>
    <option value="355">Children</option>
  </select>
  <select name="cause[1]" id="cause1" class="cause">
    <option value="">Cause to Support</option>
    <option value="993">Medical</option>
    <option value="355">Children</option>
  </select>
  <input type="submit" name="submit" value="submit" id="btnSubmit" />
</form>

JavaScript

$("#myform").validate();
  $(".cause").each(function () {
      $(this).rules("add", {
          required: true,
          messages: {
                required: "Custom Message For required"
            }
      });
  });
  
  $("#btnSubmit").click(function(e){    
  	var isValid= $("#myform").valid();  
    if(isValid==false){
    e.preventDefault();
    }
    else{
    	alert("Validate Successful.");
    }
  });