restrict access Irule needed

It's a little unclear what you're trying to do, so I'll assume you only want to allow access the URL/VIP (abc.f5.com) from the two listed addresses - and that you want to use a data group to store those addresses. If that's the case:

1. Create an address-based data group. Example (my_ip_datagroup):

   10.1.11.49 mask 255.255.255.255 
   10.1.11.50 mask 255.255.255.255
   

2. Create an iRule like this:

   when CLIENT_ACCEPTED {
       if { not ( [class match [IP::client_addr] equals my_ip_datagroup] ) } {
           reject
       }
   }
   

You could also do this in a packet filter rule and prevent the 3-way handshake that the above iRule will allow.