How do I manage POA for a relative who has stock, a home to sell, an IRA and bank accounts?

Forget beneficiaries. No one is a beneficiary until there is an estate to handle.

Who is/are the joint owners and of what assets? Can you not resolve the shared ownership problem?

I think that I would first use the money with no other names on it.

If she is the primary owner of the joint accounts, then that money likely should be used for her care. You know if she is the primary owner by her being the one who pays the tax on the interest.

As for benefactors, that's only if there is money left over after being spent on her care.

Is the house only in her name? Who else's name is the house in?

Since you are on a joint account with her, how are you related to her, i.e. daughter, son, sister, brother?

Who's the joint owner? Do you know them?

Are you also the Executor of her estate? Are the 'inheritors' in the Will the same as those listed on her accounts? Do you perceive that there will be assets left when she passes? (not that we can ever be sure!)

Could you explain what you mean by "no names attached?"