If you just want to know if one DLL supports ASLR, then load it into CFF Explorer, go to the Optional Header section, then click on the
DllCharacteristics row. If "DLL can move" is checked, then it's ASLR-enabled, otherwise it's not.
If you want to do a lot of them, I would write a Python script that enumerates all DLLs in a target directory, then checks them using the pefile module. This gives you access to all sorts of information, including the
DllCharacteristics field of the PE header, which you can check to see if
IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE is set. That'll tell you whether it's ASLR-enabled or not.
In terms of preventing them from loading, there's not much you can do. However, you can use EMET to set Mandatory ASLR on a process to enforce that every DLL loaded gets ASLR enabled, regardless of whether it's set in the PE file or not.