Manage serial port from Javascript on HTML page : which language for library?

My company has developed a hardware device which can be managed throught serial port according to a specific protocol, so we developed a C library to handle it for heavy client on Windows.

Now we are asked to make it available using a web interface, no engine inside, just with HTML+javascript on a local computer (ie on a kiosk for example), we don't need to make it available through internet so. But it's supposed to be a kind of library for customer to built-in this package in their own local web application (so with exposed/public functions just like a DLL). The focused OS is Windows, we don't speak about Linux at this moment.

I have looked for the best suitable technology to handle it, but I still hesitate on the language to choose. I have read a lot of messages especially on stackoverflow, but it's not obvious for me.

May I use a Java applet directly handled by javascript ? The jar has to be signed, and it's not free as I see ? I also heard about Java WebApp, could it be applied on this case ?

May I use a C# library with Node.js (or another javascript framework) ?

Could you give me some advices on that point, and the known problem choosing one or another language ?

Thanks