Hi Ahava, 'Companion (s)' means individuals you are closely associated with, and is nowadays used in such phrases as 'travelling companion', 'home companion to a senior citizen', 'companion website', 'companion volume (of a matched set of books)', suggesting a close mutual relationship of some sort. 'Company' has a more general meaning of the people surrounding you, your milieu; it does not suggest such a close interpersonal bond. A person could enjoy good company without having any close companion among them.
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