A medical POA is only good for making medical decisions on your Mom's behalf if she can't make the decisions herself. A financial POA gives you the right to handle finances on her behalf. You can buy the POA at an office supply store like Office Max. You fill it in and have your Mom sign it. Alternatively, google POA & you may come up with an online form. Good luck to you. I hope things go well with your Mom.
The medical cover for your mom does not cover her financial needs. This cover is only meant to cover her when she is in poor health. You should make other arrangements with your local finance management office to determine how you can cover her expenses.