Karen doesn't like driving to the local bank branch, but doesn't think that it is secure to do financial transactions on her phone. what is the best banking option for her?

I would go with direct deposit.  The banks use super encrypted links that are VERY difficult to hack.

I think that she should feel safe with online banking, but in case she were suspicious that her computer is having an issue with malware maybe because of a weak anti-virus program installed or having downloaded something odd on the internet, she could still decide going to her local bank for maximum safety.