OMA,
my sister-in-law's maid also seems to have mental problem. Always don't know what she's doing. It's better to let her to go home otherwise if she get mental attack in your home, then it's very dangerous.
my phillipines maid is quite good!
So...I think...perhaps...you can pick some maid in early 30s, got their own kids (must over 6 to 7 years old so that she will not miss her kids too much)