Must comply with POCO's and the manufactures requirements not all are the same. Some allow bonding to occure in the common gutter. some use the common area where the meters are. Really depends on the equipment. Size in accordance with the service wire size. Art 250.
I agree with Sierrasparky. There are variables to consider.
Locally our POCO allows grounding electrode connections in the meter base (some don't) and the bases I have seen have a grounding electrode connection on the neutral buss so it's kinda a no-brainer here.
If you can't bond from the meter socket, one option would be to install a grounding electrode conductor from each service disconnect,
There are a few jurisdictions that ask the the grounding electrode conductor be connected at the weatherhead. Code permissible, but again POCO may have a say.
Since you have a 3 gang meter socket, you will have multiple service disconnects. These disconnects may or may not be grouped depending on your area's use and interpretation of 230.40 EX #1. Either way see 250.64(D) "grounding services with multiple disconnecting means enclosures." It nicely lays out your three options. As others have said, probably simplest if poco allows GEC in meter base and the socket has extra lug(s) for this purpose.
Is there service disconnecting means in the same cabinet or just meter sockets only?
If sockets only the GEC can land here but does not have to, and as mentioned some POCO will not allow it.
It can connect to any common point ahead of the service disconnecting means including at the point of connection to the service drop or lateral. Or you have a couple options of how to connect to each of the service disconnecting means, most common is probably to run one GEC and make taps to each disconnect enclosure.