Mother needs 24/7 care. Can we pay ourself the same hourly rate as we pay our helper?

Yes, your mother can pay you. Have a legal contract in place, and follow all the rules for estimating and paying taxes. I take it you are spending down for Medicaid. If you have an Elder Law attorney helping with that process, contact the firm about this, too.

SherryAC, I seen nothing legally or morally wrong with using your mother's funds to pay you for providing her care, but a notarized Personal Care Agreement (PCA) must be in place to avoid a future Medicaid look-back penalty. The hourly rate you pay yourself should be reasonable, e.g. no more than prevailing average rate and the total for all care shouldn't cost more than a facility's care would cost for the level of care she needs. In other words, if you weren't providing her care, determine what her care would cost and don't exceed that amount. And if the care you provide costs considerably less than the alternatives, then I suspect a Medicaid investigation will be less demanding. Since you're living in her home and if you do pay yourselves with your mother's funds, then you should pay your share of utilities and possibly rent, as well. Check with your state's Medicaid office to find out what would be in line with its rules. AgingCare.com has information about PCAs at https://www.agingcare.com/articles/personal-care-agreements-compensate-family-caregivers-181562.htm

Most would advise no on paying yourself. Especially not without a care agreement.
Do you have hospice or palliative care for your mom? I see she has cancer.