OEH is halfway up the hill between The Pete/Upper campus and Towers/lower campus. It’s right on O’Hara across the street from Benedum (The engineering building). TBH 5-7pm is still on the early-ish side for classes (in terms of night class, those are generally 6-9pm classes) and yes it’s totally safe. Since you’re still in the middle of campus you are completely fine and within a 5 minute walk of practically everything. You don’t need to worry about a bus or shuttle…it’s not a hard distance to walk.