As others have said, she doesn't need a solicitor. She needs to spend the money as quickly as possible in a manner that the UC Decision Maker will think is acceptable.
If you have more than £16,000 in total then you will not be eligible for UC. If you have between £6k and £16k then your UC will be reduced on a sliding scale.
You need to bring the amount you have down below those figures. But you have to do it in a way that is not counted as "deprivation of capital".
If you spend the money "extravagantly or imprudently" then they will count it as though you still have the money. Or, even if you spend it prudently but a significant purpose in spending it was to be able to carry on getting UC then they will consider that you still have the money.
So, you have to spend the money as you might if you weren't on benefits.
If you have any debts or a mortgage then it is perfectly ok to use the money to pay off any or all of your debts, that is fine.
The UC Regulations also say that it will be ok if "they purchase goods and services and that expenditure was reasonable in the circumstances of that person’s case." [UC Regs, Reg 50(2)]
So, for example, if you were to buy a newer, more reliable car, that would likely be fine (unless maybe you're buying a Porsche or something like that) or actually buy a car if you don't currently have one.
In contrast, if you were to buy a second car but you are single and can provide no reason why you might need two cars then they likely wouldn't count that as reasonable.
Likewise, if there were any essential repairs that needed doing on your house then that would be fine as well. Perhaps the roof is leaking or the boiler is broken? Or you need to deal with damp or the house needs rewiring etc.
Or if your home is short of reasonable quality furniture, fittings and equipment, it could also be perfectly reasonable to spend a reasonable amount improving poor living conditions.
But that likely wouldn't include buying the very top-end most expensive things.
Likewise, it may be reasonable to take a reasonable holiday, but probably not an extravagant one.
It is very difficult to give examples of what would be counted as "reasonable" as different UC decision makers may vary and it will depend on your individual circumstances and your previous spending patterns.
You should also keep receipts and a record of how you spend any of your capital (even if you lose entitlement to benefits — but may claim again in the future) as evidence to support your case if you are questioned.
In summary, any large items of expenditure: new furniture, family holiday, repayment of debts etc may be accepted as reasonable expenditure, which you would have made, had you not been receiving benefits.