object Object in select inputs datatables

It turns out that it implements the select input and works well in all the columns, except one. It shows me [object Object] in the selector of that column.

{
  "sClass": "alignRight",
  "data" : null,
  'render': function (data, type, row, meta) {
  var nombre = row['nombre'];   
  var apellido = row['apellido'];   
  return ' ' + nombre + ' '+apellido+' ';
  }                 
}

is in this column where I get [object Object] when the first and last name of the users should appear. the call is executed by ajax and returns a json. I read that there would be no need to use 'render', but in that case, as I call the variables name and surname. If someone could guide me, I would appreciate it. Greetings.