E-6 stabilizer contained formalin as a preservative. Modification in Kodak and Fuji formulation of E-6 chemistry placed some formalin in a previous bath and so formalin was not any more necessary in the final bath. Kodak and Fuji call this last version of final bath without, or with less, formalin as "final rinse". So stabilizer = a final bath with formalin, final rinse = a final bath with much less formalin, or no formalin. Photo Engineer wrote some posts about this.
I don't know if the same can apply to C41 chemistry. Is formalin present in some C-41 bath? If the answer is no, I would use E-6 "stabilizer", not E-6 "final rinse", for negative film. If the answer is yes, I suppose you can use both styles of E-6 product for your C-41 film as the final thing is not strictly part of the processing, is just a general aid for good drying and preservation and would apply more or less to any film I do believe. B&W film does not need formalin in theory because silver is already a bactericidal substance. In practice, I would use formalin also for B&W film unless PE explicitly warns against its use.
I personally use Ornano E-6 kit and it uses a final bath with formalin. That would be a "stabilizer" in Kodak parlance. (We just say imbibente which is easier ).
Some years ago, the formalin content of Ornano E-6 final bath was reduced, but formalin is still there. Formalin content was reduced especially to reduce workers' exposition to formalin vapours in laboratories. The thing is not so dangerous in the concentration and use of the typical home developer. I just add 10ml of 4,5% solution to 500ml demineralised water which I keep hermetically closed. I would just buy final bath with formalin and be sure that it helps preserving any film however treated.
Do wear glasses when dealing with chemical substances.