GrannyBing - anti bark collars aren't the answer to a dog who is desperately lonely, having been adopted from goodness knows what background and is then abandoned for long periods on its own.
The dog is suffering from separation anxiety, that's why dogs howl and bark when left alone. Most dogs can be trained to tolerate periods alone, ideally not much more than 4 hours on a regular basis, though I accept that isn't always possible.
So, the honest, brief answer is No, anti bark collars won't work in the circumstances you describe. The other solution would be for the owner to pay for day care or at least,for someone to come in during the day and walk the dog for a couple of hours.
Sorry to be blunt. If your neighbours are prepared to do a bit of work, they can help their dog to learn to be alone for short periods initially. Leave the radio on, leave the dogs food in toys that mean the dog has to work to get them out. Leave a kong, stuffed with some of the dogs food, some carrots/cheese etc and freeze it so it takes the dog half an hour to eat the jollies. All these things tire dogs out, thinking is much more tiring than running about for 10 minutes.
Sorry to not come up with easy solutions, there aren't any.