My aunt has a bank account in the US and we have tried to gain access to get the money transferred to the UK in order to pay nursing fees urgently, but are having problems with the bank as my aunt has dementia and they are talking about power of attorneys being made in the US (each state has different rules apparently) or their equivalent of Court of Protection. As it is her money and for her use is there anything other than this that can be done?
If a small amount, it might be even worth considering leaving it until after death, then her heirs pursuing collecting it via probate court at that time.
Could the US embassy help you?
Before she developed dementia she needed to assign someone as her PoA here in the States. Now the only options are either for some willing person in her family to pursue guardianship or conservatorship to become her legal representative, but this requires being here in the States and paying for it, which can cost thousands.
Or, you tell the NH she has no legal representative and for social services to recommend her case to a judge who will assign a 3rd party legal guardian. Then they will manage all her affairs and decisions going forward. No one else will have insight into her accounts or business or decisions until she passes.
It doesn't sound like you're here in the States, so this is the best solution, IMO.