If both AC generators fail, you are stuck to standby power from the battery (batteries, depends if you have a single or dual battery installation), unless you can start the APU and get it on the busses.
Under Stby power you will have (for about 20-30 minutes):
1) Stby attitude indicator (also shows ILS information)
2) Stdy airspeed indicator / altimeter (illumination only, the standard instrument is mechanical)
3) ILS 1
4) VOR 1
5) Stby RMI
6) FMC 1
7) DEU 1 showing essential engine data on the upper center DU
8) Cpt outboard DU
9) Capt. EFIS panel
10) I haven't got the schematics here, but IIRC ADIRU 1 might also be powered by the Stdby system.
You will not have any autopilot components working.
The engine EECs will be running off the EEC alternators mounted on the respective gearboxes.
Rgds,
Jan