How to afford night nurse?

Not sure what the solution is but I know this must be very stressful for all. Perhaps the hospice doctor can review your dad’s meds and see if there is anything he can offer to help dad rest at night. Make sure they have checked him for a UTI.
Poor mom. This must be very stressful for her as well. What exactly would the night nurse be expected to do? I ask because many times if it’s a sitter all they do is call for help and the same 20 min would be needed until help would come. Push back on hospice to get them to investigate dad’s situation a little closer. Let us know how it resolves.

Its amazing how the health care professionals so casually say "he needs a night nurse" or he needs more supervision as if it can easily be done. Yes, as others have said, it may be time for a SNF and Medicaid. Contact APS and/or local Area on Aging. Maybe there are options for in home care paid by Medicaid (but don't get too hopeful with that), but at least make APS aware that there is a vulnerable adult(s) with no resources for care.

nursing home.

It is likely that he needs a nursing home rather than memory care. Not even memory care will be monitoring him 24\7. Unless a private companion is hired, yes on dad's dime, then a nursing home may be the only solution.

You may want to check any nursing programs that could be in the area. They may have some students willing to volunteer for this. They can add volunteer care to their resumes down the road. Volunteer work I did over the years helped me land several jobs.

It does not sound like you need a "Nurse" if no medications are being given or dressing wounds then a "sitter" or "companion" might be a less expensive option. Someone to be there to help him to the bathroom, help "re-orient" him and keep him from wandering or harm.
Someone like this would not be paid as much as a nurse.
You can contact an agency and ask, or hire privately. The problem hiring privately is background checks and all the taxes and paperwork involved. And finding someone that is honest and trustworthy. You could ask a current employee of the facility and ask if they know anyone looking for hours. Might even be able to split the hours between someone leaving a later shift and someone working an early shift. (If they are allowed to work privately)

Ditto to 97yroldmom's comment about checking for UTI to discount that as a culprit and pinpointing exactly what good a night nurse would do. Is he getting up to use the bathroom? If so, and he is already wearing incontinence undies, can a potty chair be put in his room so he at least doesn't have to go far? Or, would a hospital-style bed that has side rails be practical? I wish you all the best as you work towards solutions!

Hmm with everything taking affect with cvid19 . I would ask if u can have a private care aide come in durning night .. there are resources to help with the costs . If I may ask what state are u living ? I do private home health care and would be more than willing to assist

Since he is on hospice, check with their insurance company - who are handling the finances for hospice. He may qualify for an aide,

Because of the covid issue being the hold up for moving to memory care, you should ask the facility or hospice nurse what they can do to accommodate his needs since this is through no fault of his own. Assuming they have been in quarantine all this time, they should not have exposure to the virus. Can you or another relative (who has also adhered to quaratine) go stay with them until lockdowns are over? -- I understand they may say no one can go in during lockdown, but if hospice is saying they need an overnight person...someone will be going in. Preferably it would be someone you know who has not be exposed to virus. Better you than someone you don't know.