So your current View version is 5.01.   What is your current vCenter and vSphere version?

Vcenter and ESXi are on 5.0

Vcenter - ESX - View Composer - Replica - Security Server

If I upgrade the Vcenter and ESXi first to 5.5 U2 ,the VDI view 5.0.1 is not supported on ESXi 5.5 as per VMware compatibility document .

Is the path still fine to upgrade ?

Vcenter -- ESXi -- View composer -- Connection server -- security server

Present View Environment versions -

vCenter : Version 5.0.0.623373

ESXi : VMware ESxi 5.0.0 914586

View Composer : 2.7.0.481620

Connection Server-1 :5.0.1.640055

Connection Server-2 :5.0.1.640055

Security server:5.0.1.640055

I forgot about that. I stand corrected. I think you are going to have to upgrade view first then your vcenter.

VMware Product Interoperability Matrixes

Make sure you are on update 1,2, or 3 and then do the view update.

I think that is fine if your going to upgrade all of them in a single night.   If you want to opt for a phased approach such as updating vCenter/vSphere one night and doing View another night you would need to go with vCenter/vSphere to 5.0 update 2,   then later do View 6.01,  and then at another time go back and upgrade vCenter/vSphere  to 5.5.