How to travel to Versaille best way on wheelchair on 30th of september from 32 Rue des Plantes?

I believe the best way from Paris (32 rue des Plantes) to Versailles (Chateau Rive-Gauche station) would be Tram 3a then RER C.
 
From 32 rue des Plantes in Paris you'd make your way down on street until Tram 3a station Jean Moulin.  Trams in Paris are all fully wheelchair accessible, roll-on/roll-off without assistance.  Take Tram 3a from Jean Moulin to Pont du Gargliano stop, its west terminus station (and listed direction for your trip will be Pont du Gargliano / Hopital Europeen G. Pompidou).
 
From Pont du Gargliano, wheel over to the RER C station "Pont du Gargliano" and take RER C in direction Versailles Chateau - Rive Gauche.  For both the start and end stations of your trip on the RER C you'll need to book access help at least 24 hours prior to your travel.  You can do this by email as detailed on the Paris train accessibility page.
 
In terms of ticketing you'll need two tickets, one for the Tram and another for the RER C, as those are not valid transfers on a single ticket.  The tram ride requires just a normal Ticket t+ (same as a Metro or bus ticket).  But the RER C requires a billet origin-destination / RER ticket for your start/end stations.  You can buy both tickets ahead of time at any automated ticket vending machine or ticket window.  They don't start their validity period of 90 minutes until you validate it in a ticket reading machine.
 
I double checked on train/track/station maintenance works closures for the RER C and didn't see anything listed for 30 September 2023.  There is a strike planned for Sept 26, 2023, but that should only affect (reduce quantity) of trains for that day, not on the 30th.  Although, it's a good idea to monitor the Transilien.com train website for updates on further strikes ("mouvement social").
 
Hope this helps.