Don't take money from the IRA. Don't get a loan from your 401K. Using retirement funds is far more expensive for your future.
Don't get a home equity loan or any loan tied to your car or home, that just puts more of your resources at risk.
In general a consolidation loan is used to lower the interest rate. The problem with a credit card debt is that if you are making the minimum payment it will take many years to pay off the debt. The minimum amount isn't designed to payoff the debt quickly. You need to set a goal to pay more than the minimum to reduce the interest.
You may find out that you can't get a loan based on your debts and income that will give you a lower rate. You might not be able to find a credit card that has a low or zero interest rate. But if you do get a new loan look for a payment plan that you can afford, assume that your relative will stop making payments.
The way to do it is for you to pay as much as you can to reduce the balance quickly. Then continue to have your relative make payments to you. If you don't want to charge them any interest above what is paid to the credit card company, then once they have paid you back for the interest and the principal then they are done.
Paying it off as fast as you can will also protect you if they stop making monthly payments, the balance will be closer to zero if they stop. If they keep making payments to you while you are paying off the loan, then that gives you more money to bring the balance to zero ahead of schedule.