s̶c̶i̶p̶y̶ ̶i̶s̶ ̶p̶r̶e̶s̶e̶n̶t̶ ̶i̶n̶ ̶P̶a̶r̶a̶V̶i̶e̶w̶ ̶5̶.̶7̶
Edit : scipy is NOT present in ParaView 5.7 on windows.
To answer your questions :
Is there any way to install external python modules into Paraview?
Not yet. It should be possible in 5.8 if all goes well
If not how can I import mat files?
Open them in matlab and save them into .vtk format