sshfs with a jump host

sshfs -o ProxyJump=B_host C_host:/<path> <mountpoint>

From https://serverfault.com/questions/941934/sshfs-over-a-jumphost where John Kearney and Omar Buhidma suggest using ~/.ssh/config, this will accomplish this simpler syntax:

Host <host alias>
    User <host_username>
    HostName <host_name>
    ProxyJump [user@]<jump host>[:port]