If I intend my pre-fasting meal (suhoor) for the Monday and Thursday fasts to be a charity (sadaqah), will my mother receive the reward for my fasting?

If you intend that the iftar (definition) your mother provides you is charity from her to you, this intention of yours is not in place, because the doer of the action is the one who determines his intention. And if your mother has not intended good with her giving, then your intention will not benefit her, due to the Prophet’s (peace be upon him) saying: "Deeds are only by intentions." Some scholars are of the view that a person who performs an act whose benefit extends to others will be rewarded, even if he did not intend it, citing the Almighty's saying: "No good is there in much of their private conversation, except for whoever enjoins charity or that which is right or conciliation between people. And whoever does that seeking means to the approval of Allah - We will give him a great reward." (An-Nisa: 114). However, if your mother intends, by providing your iftar, to draw closer to Allah, then she will receive the promised reward. And your mother will benefit from your righteous deeds and will have a reward in them, especially if she enjoins you to do them, guides you to them, and helps you with them.