These fine people will look after the wee squeakers: http://www.londonwildcaretrust.co.uk/ Their (24 hour) phone number's at the top of that page. My gf, who's hand-reared dozens of pigeons, assures me that London Wildcare won't euthanise your birds. She also tells me that they need to be fed parrot formula with the sinister-sounding 'syringe and balloon method'. In the hands of an inexperienced person there's a good chance of the birds aspirating their food and suffocating. I'm sure your mum would be heartbroken if that happened.