This right of way is usually referred to as an easement and should be registered on both sets of title deeds , a legal easement that is registered against the title will bind future purchasers under section 62 of the of property act 1925. By planting a tree and building a fence and other structures the neighbour could have caused interference or wrongful obstruction and this must be challenged as it will probably affect the property value.
I agree with F30 and BM, suggest to your daughter that she takes all the information, if possible with photographs of before and after, to a local Solicitor and ask him to write to the neighbour asking him to reinstate the right of way, if he does not your daughter may have to go to court, but court should be the last resort.