keypad debouncer configuration RC Value
Yes, either one will work - the cap doesn’t care as long as it has a charge/discharge path. I have a preference for #2 since the cap discharge path to the switch is via GND. 

The RC time constant you select depends on how much contact bounce you have. Figure on the order of ms to tens of ms, but check with a scope if you can.

If possible consider adding a Schmitt-trigger buffer if your receiving device isn’t of that type. 

Here’s a reference by Jack Ganssle, a well-known contributor to EDN and other electronic pubs. https://my.eng.utah.edu/~cs5780/debouncing.pdf