Your Ms seem to be unselected. What happens if you select both (you can just ClickDrag over them, or click the circles to the right in the Layers palette), then try again?
I already tried that, for some reason in the picture its not selected. It keeps greyed out...
Are any layers or objects locked?
As Ton suggested, your next best step would be to reset references.
If that doesn't work, try uninstall/reinstall with the Adobe CC Cleaner Tool. https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html
In the screen capture, the two objects do not seem to be selected. I don't see a bounding box around them, but maybe you turned off the visibility (View > Show Edges or Hide Edges).
If the objects are selected and the Blend tool is still grayed out, try choosing Object > Blend > Make.
Problem is that I am unable to select Object > Blend > Make
Jacob and Barbara are right, your control panel says "Geen selectie".
No selection > nothing to blend.
My bad for some reason its not selected on the picture. I did select them.
Did you try to reset preferences?