Hi Jenn!
Ah, I thought this sounded a little familiar
So, no, I would not remove main navigation from the homepage. But, I would do this:
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Have universal navigation for the website including all the major links.
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For the sake of users, yes, divide the contents of the homepage into two side-by-side sections in whatever way offers the best user experience (one side for the club, one for the wedding service).
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Have each side link to its respective set of content, but with all normal navigation intact in both sections.
You honestly do not want Google to view this as two separate businesses. You don't want them to be confused about whether (222) 111-2222 is the number of a restaurant or a wedding venue. You want to promote the whole thing as a single brand, with a single GMB listing and supporting citation set, for a business that offers a varied menu of services (dining, events, etc.). But, for the sake of users, you simultaneously want them to be able to quickly access the content describing the services in which they have the most interest. So, if they happen to enter to website on the hompage (instead of on the main page for weddings) you can certainly give them a big, visual cue about how to navigate to that section of content.
Ranking for these different types of searches is just going to come down to good old SEO, both local and traditional, and all of the marketing you can do to promote the variety of services offered. Authoritative local links to the main page for the weddings (for example) will help in your pursuit of visibility for wedding-related searches in your city, while getting great restaurant reviews on Yelp should bring in diners.
I'd seriously urge the owner to view their brand as a brand - one that offers a variety of services, just like a general contractor who does roofing, remodels, fence building and deck design. Each is a different experience, for a consumer with a different need, but all needs are being met by the single, unified brand.
Hope this helps!