Copyrights last for a specific length of time. Nowadays in the USA (following an updating in the 1970s) the period is, I believe, 75 years. After that time, the material passes into public domain.
However, a specific performance or a specific printed edition of the music could still be subject to copyright, and the royalties would be paid to the performer or the publisher of the printed music (among other possibilities). And, in some cases, a composer (or the executor of their estate) may set things up legally so that their estate would have rights and responsibilities following their death.
As for the specific classical composers you asked about, I honestly don't know how their estates were set up. It is a great question for further research!