Add Alt attribute to image served with php

just add it in…

  <div class="bd-layoutcolumn-20 bd-column" ><div class="bd-vertical-align-wrapper">
    <img alt ="my alt tag" class="bd-imagelink-3 bd-imagestyles   "  src="https://wordpress.stackexchange.com/questions/244847/<?php echo theme_get_image_path
     ("images/b56392d722ada5890c6d2f29f1dbde4a_logo.jpg'); ?>">

if you’re going to make it dynamic you’ll need to add the php. Something like this if you’re in a loop:

  <div class="bd-layoutcolumn-20 bd-column" ><div class="bd-vertical-align-wrapper">
    <img alt ="<?php echo get_the_title();?>" class="bd-imagelink-3 bd-imagestyles   "  src="https://wordpress.stackexchange.com/questions/244847/<?php echo theme_get_image_path
     ("images/b56392d722ada5890c6d2f29f1dbde4a_logo.jpg'); ?>">