Tribikerun is recommended often. I can’t speak for fitting but nice people and I think owner was/is pro triathlete. They can be busy so I’d try to make appointment.
So for new tribike and unused to traffic, I’d say two options, (1) stay in PGA – but I’m not aware of bike trails and there will be some car traffic, (2) drive down PGA, after crossing US1, turn left into Publix and park. PGA turns into A1A, aka, Jack Nicklaus Drive, and if you take it you’ll go on Singer Island and have 5-6 mile ride till you come to big bridge. You can ride over bridge and turn around, or turn around before bridge. That makes a 10-12 mile out-back you can repeat. There is nice bike lane on both sides, which is pretty smooth except for a little bumpy stretch through the mangrove forest . Generally not too much traffic either. You won’t see the ocean unless from top of bridge, but great bay views. You’ll be able to get in aero position for most of time on this, which I doubt you can do much at all in PGA National.
There might be better areas inland, but I never rode much down there except along beach. I’d take any new rider to Singer Island.
Going north from Publix along US1 and turning onto Ocean Drive, aka A1A, there is also bike lane. However, that stretch, which is very scenic along ocean, gets alot of tourist and local traffic. Also northbound there is parking to right of bike lane and you have to be careful of people opening car doors.
Have a great visit with you mom.