"Expecting company" is like expecting guests to visit and or come over. To say "company is overdue" that means basically they should be there any minute and or they are becoming late. The definition if you read a dictionary you will see depending if it's used as a noun, verb, etc. The meanings are in any word you look up. sometimes it can have multiple meanings. So yes it is a company like for a business ( but separately ) it can be just people coming over to visit.