I've learnt not to apply standard definitions when it comes to human relationships. Because, there is no black and white when it comes to human behavior. We are mostly about what we learn socially, and what we inherit from our upbringing. Having said that, there are a lot of grey areas between black and white. A Mother by definition is the most caring selfless person on earth. But in reality, she can be a nasty evil too. There are extremes, both good and bad. But on average, there is a mixture of both. Nice, good, somewhat good, somewhat bad, bad, evil etc.. So, only your friend alone knows which category her mom fits in. If the mother has always been nice or on a gooder side, but she has turned out to be a sour, bad soul off late, then your friend should assess what's caused the changes. Perhaps her health, mental health, any bad incident, etc..etc... However, if she has been like this forever, then there is nothing much left to bother about this. She needs to act quickly by letting her H and (if needed in laws) know everything before it is too damaging. Perhaps, her H can stand up for her or chose to ignore his MIL's comments. Both can eventually shut this old woman off, or at least less aggressive.