Select user having qualifying data on multiple rows in the wp_usermeta table

I would use this query:

SELECT
  user_id
FROM
  wp_usermeta 
WHERE 
  (meta_key = 'first_name' AND meta_value="$us_name") OR 
  (meta_key = 'yearofpassing' AND meta_value="$us_yearselect") OR 
  (meta_key = 'u_city' AND meta_value="$us_reg") OR
  (meta_key = 'us_course' AND meta_value="$us_course")
GROUP BY
  user_id
HAVING
  COUNT(DISTINCT meta_key)=4

this will select all user_id that meets all four conditions.