Granny would probably be the last person suspected of armed robbery of the most highly secured banks in this area. That is exactly why Granny makes the perfect gangster to pull off a heist of this magnitude. Infiltrate the bank and access the monitors to gain access to secured areas and collect the loot that is within them. If you see any security guards then you should put them into early retirement and hopefully their granny wives will collect their pension. Use the tab key to select the weapon shop and upgrade to more awesome weapons with the cash you collect.