[twic]

Wikipedia calls them all Serbo-Croatian [1], more or less:

> Serbo-Croatian – also called Serbo-Croat, Serbo-Croat-Bosnian (SCB), Bosnian-Croatian-Serbian (BCS), and Bosnian-Croatian-Montenegrin-Serbian (BCMS) – is a South Slavic language and the primary language of Serbia, Croatia, Bosnia and Herzegovina, and Montenegro. It is a pluricentric language with four mutually intelligible standard varieties, namely Serbian, Croatian, Bosnian and Montenegrin.

There's also some story about how these all derive from Shtokavian via Eastern Herzegovinian, so those might be useful names too.

And, of course, how could we forget the Balkan sprachbund [2]!

[1] https://en.wikipedia.org/wiki/Serbo-Croatian

[2] https://en.wikipedia.org/wiki/Balkan_sprachbund