All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Indeed, you did well by spending on your mother and being concerned about her, so may Allaah reward you.
We advise you to continue being kind and dutiful to her as she is your gate to Paradise; for more benefit, please refer to Fataawa 82254 and 87019.
If your mother needs someone to spend on her, then all her children are obliged to spend on her and not only yourself. Therefore, you should inform your brothers about this matter. However, if you want to spend on her on your own, then you may do so and you will be rewarded. Moreover, your brothers are obliged to be kind and dutiful to your mother and they should always keep in touch with her and they should visit her as much as possible. If one of them is not able to visit her, then he should contact her and ask about her.
The same thing applies to their wives; they should visit her and find out about her condition. However, they are not religiously obliged to do so, but keeping good relations with the in-laws is Islamicly required.
For more benefit, please refer to Fatwa 90201. For more benefit, please refer to Fatwa 87240.
Allaah Knows best.