+1 on giving your mom your old phone.
Note 2 will be great lalo they can zoom the text to a very large size.
Texting will also be better with a biggish keyboard, haptic feedback and the conversation style texting that the old phones don't have.
J5 or J7 kung ganun. The slower/budget samsung phones can be frustrating to use.
Never used the chinese phones so I can't recommend them.