You're right to worry. Without a durable power of attorney for healthcare, you won't be able to participate in those healthcare decisions. If you don't have durable power of attorney
for healthcare, you're pretty much powerless to help your mother if she becomes incapacitated. A guardianship gives you the power to take physical care of her. A conservatorship allows you to act in her stead to care for her estate. Generally, it's a good idea to go to court and get both at the same time.
The most common reasons for needing a guardianship are a sudden decline into dementia or Alzheimer's, or a serious medical event, such as a stroke or an aneurysm. You'll need to get a doctor's opinion that your mother is incapacitated, which I've seen take as long as three weeks. That opinion gets filed with the local court along with a petition for guardianship and conservatorship. Your mother would be appointed a guardian ad litem to represent her interests in the court process.
Although you can get temporary guardianship or conservatorship on an emergency or temporary basis, it's significantly more expensive, and obviously more stressful. That's why when clients balk at paying for having a power of attorney for finance or healthcare drawn up, I just cringe, because the alternative is unbelievably complicated and expensive. Attorney fees alone could run $2,500 to $4,000 for an uncontested guardianship (meaning that your mother doesn't challenge your attempt to do so in court, or a sibling doesn't disagree). The guardian ad litem's fee will be anywhere from $500 to $800.
What's more, as conservator you'll then need to file an annual accounting with the court listing the assets in your mother's estate. In the state where I practice, this listing is reviewed by a court-appointed commissioner of accounts (other states have other names for this person, but their duties are roughly the same). Trust me, having to go to court to be named your mother's conservator is nothing anyone wants to do. The easiest route, for you and your mother, is to have a durable power of attorney for healthcare and finance. I'd recommend that you do your best, perhaps with the help of a trusted family friend, to persuade her this is the easiest and least expensive route.