Hi leothanhtiep
1 - I think it related to Easysocial configuration as if I assigned this page to Protostar - a standard template of Joomla, it also noticed 404 error, could you contact StackIdeas for this?
2 - There is no option in Easysocial to configure this column settings, I just updated some files on your site so it shows 1 column now:
/components/com_easysocial/themes/wireframe/groups/default/items.php
/components/com_easysocial/themes/wireframe/pages/default/items.list.php
/components/com_easysocial/themes/wireframe/videos/default/item.list.php