It’s been a while since I left the DWP, but as far as I can see not too much has changed. The problem with any sort of information from solicitors or DWP staff is that it’s difficult to speculate the outcome of a hypothetical situation.
Whilst your friend has over £16k, she will not be entitled to UC. ( there is nothing to suggest that any part of an inheritance could be disregarded ).
The decision as to whether deliberate deprivation has occurred can only be made after the money has been spent. It sounds like a ‘Catch 22’ situation, and in a way it is, but only because it’s so complex.
There really are few generalisations. If I give the example of buying a car.
a) person with physical health problems, living rurally, no public transport, etc replacing their old, unreliable car with a fairly modest newish car - this would probably be fine.
b) person who is young, fit, living in a town with facilities nearby, buying a new BMW, - probably not OK.