My wife does not have POA of her Mother but we are taking care of her. Thinking of Guardianship?

A DPOA vs. a Guardsnship are very very different. DPOA usually works for most if done properly & if the elder is competent to do one. To me a guardianship is often the nuclear approach used when the elder just flat will not allow family to help them be safe & secure & healthy and you need a court order to come in and do what needs to be done. Also guardianships have different types - depending on your state law - and require some sort of reporting to the court....just a much more involved process. Also if her moms dementia is such that she is not at all competent, you just may have to go guardianship route.

I came across this article on Aging Care website that I hope will be helpful for you. There are quite a few comments for you to read through, too.

https://www.agingcare.com/articles/how-to-get-guardianship-of-elderly-parents-140693.htm