I would echo the advice to dispose of the billboards. I can imagine that there are many complications related to owning these US-based properties as well as tax issues to deal with in both countries. Depending on the form of ownership involved there will be capital gains resulting which may create a significant tax liability if it is all realized at once. Clearly she needs some careful advice regarding the tax implications on both sides of the border. 
There don't appear to be any plans for the waterfront lot so this is an untapped source of liquidity if it were sold. Again, what will be the tax implications?
It appears that Yvonne is living a lifestyle well within her budget. I wish her well.