Going to company’s social functions would be spending time with co workers in a non work environment such as a company party or going out with the guys/gals.

2.) To go to a company’s social functions means that you attend non-work-related events that are sponsored or encouraged by the company you work for — the company’s Christmas party, company golf outings, company parties of any kind, for example. The phrase normally *wouldn’t* be used to include events that are attended by you and your co-workers, but are not official company events, such as a bunch of you going out for drinks after work, or you having a party in your home and inviting your co-workers.

To go to company’s social functions? That’s an easy one an self-explanatory. It is when you work for a company and that company has a social function for its employees and you attend, is when you go to company’s social function.

2: To go to parties and events that are hosted, supported or sponsered by the company