So, Ellen thinks she doesn't have a problem, even though she's had to take Brenda's 46k life savings, AND she still has debts around 85k?! Her excessive spending is having a detrimental effect on your whole family, and it needs to be stopped!
Your whole family need to come together, with Ellen, and explain to her once and for all that this can't go on any longer. You need to make her aware, in no uncertain terms, that there will be no more bail outs, and she needs to work out a plan to pay back Brenda's money. She needs to be told, very firmly, that the spending has to stop. That no one in the family wants/needs her gifts, which she can't afford to buy anyway!
You should offer to help her make a plan, by sitting down with her to go over her finances, and work out how to get her out of this mess, by closing credit card accounts, and consolidating payments for them, and contacting companies to try to agree some sort of monthly payment that she could manage. Most importantly, she needs to be making a regular monthly payment to Brenda to pay back the 45k. She obviously has absolutely no moral conscience whatsoever, to have taken her Brenda's life savings, knowing she earns so little, when she has a good job with a very generous salary.
Instead of enabling her to carry on this outrageous lifestyle, which is having a detrimental effect on the rest of the family, she needs to be told truths, and made to feel ashamed of her actions. Until then, she will continue to do as she pleases, and your mother could end up losing her own home if Ellen gets into much more trouble and has no alternative but to ask your mother to bail her out!
Some may say Ellen is an adult and it's none of your business to interfere in her financial affairs, but when it effects other family members it absolutely becomes other people's business! You have a right to interfere, in order to protect your mother, and Brenda.