How hdrolysis of SiX4, GeX4 , SnX4 (X=halogen) is occured?

Hydrolysis of these tetra halide takes place  in  the   following two steps : 

Step-1:  In this step oxygen atom of water molecule acts as a donor atom as water molecule contains two lone pair of election . 

Attacks the central metal atom to form a co ordination bond.

And the product is an unstable  intermediate compound MX4.4 H2O ( M=central atom X=halogen) 

  

Step-2: In  step 2 there is the elimination of four HX molecule from the unstable intermediate compund   thus the tetrahalides of Si,Ge,Sn is hydrolysed, this hydrolysis forms hydoroxides of this elements.