Both social events are close by the central place in Munich (Marienplatz). You can either walk there as shown on the map (2.5 km, about 30 min), or take public transport. Public transport options:
The Old Town Hall is next to the Marienplatz, 50m to the east. It is a white building (https://goo.gl/XE2OUV), not to be confused with the large, red New Town Hall immediately next to the Marienplatz.
The Hofbräuhaus (https://goo.gl/SUUQvW) is a few minutes east and north of the Marienplatz, as shown on the map. Turn left behind the Old Town Hall into Sparkassenstraße, right into Munzstraße, and left into Platzl.