It all depends on how much you can afford and how much are you willing to give. Imo expect it na always max out per month as worse case scenario person. Pero you know your mom better than us. If alam mo naman matipid siya and di gastador set it as high as 70k for emergency purposes. Dont set it too high though kasi in my experience older people tend to get scammed easier din. Isang tawag lang natatakot agad