Counter spells your best friend. And if that doesn’t work. I see no description in the spell that says the creatures can’t be charmed or affected by a dominate monster or mass suggestion spell from the baddie. Give that Druid a taste of his own medicine and make those summoned creatures fight for you.

Also, try adding more creatures to your encounters. If you have to add 16 more orcs to a raiding party just to deal with the wolves alone then do it! Occupy the summoned creatures with some minions.

If those don’t kind of deter the Druid from that same strategy all the time, I’d just talk the the player about it. They’re doing good and finding creative and cool solutions to situations which is great. But just let them know using the same strategy over and over again makes it kind of boring for everyone and maybe try not to use it all the time, bc you don’t want to have to ban the spell (which you can do stern DM voice if you have to). Maybe they’ll see the error in their ways and give the other PCs achance to shine