She drives her sisters to the Qur’aan school and she stipulated that they should teach her adhkaar and du‘aa’s in return for that
Question

                I have someone who drives me to Qur'an class everyday. However, she gets upset when we don't test her on certain du'aas or lessons. She has said she wants something in return for driving us, and that she shouldn't have driven us (due to us not practicing memorizing a du'aa with her).

I'm very scared now because i don't want her reward to be wasted because of her statement.

Is her reward wasted if she has said "I shouldn't have given you a ride" because of us not reviewing some material with her?.
Praise be to Allah.Firstly: 
There is no doubt that part 
    of a person’s understanding and eagerness for good is that his righteous 
    deeds should be sincerely for Allah and free of any other motives such as 
    making gains, whether it tangible or intangible, even if it is only thanks 
    from the person he treated kindly or a du‘aa’ that he asks for from the 
    person for whom he did a favour. 
Hence Allah, may He be 
    glorified and exalted, said concerning His believing slaves, the people of 
    the highest levels of Paradise (interpretation of the meaning):
“And 
    they give food, in spite of their love for it (or for the love of Him), to 
    Miskin (the poor), the orphan, and the captive, 

    (Saying): ‘We feed you seeking Allâh's Countenance only. We 
    wish for no reward, nor thanks from you. ‘Verily, We fear from our Lord a 
    Day, hard and distressful, that will make the faces look horrible (from 
    extreme dislike to it)’”
[al-Insaan 76:8-10]. 
It was narrated from ‘Ubayd 
    Abu’l-Ja‘d that ‘Aa’ishah said: 
A sheep was given to the 
    Messenger of Allah (blessings and peace of Allah be upon him) and he said: 
    Divide it into portions and distribute it. Every time the servant came back, 
    ‘Aa’ishah said: What did they say to you? She (the servant) said: What else 
    could they say? (They said): Baarak Allahu fikum (May Allah bless you). 
    ‘Aa’ishah said: And may Allah bless them; we say to them the same as they 
    said to us, and the reward will still be saved for us. 
Narrated by al-Nasaa’i in
    ‘Aml al-Yawm wa’l-Layla, 303; also by Ibn al-Sunni, 277. Shaykh 
    al-Albaani (may Allah have mercy on him) said: Its isnaad is jayyid. 
    Takhreej al-Kalim al-Tayyib, no. 175 
Secondly: 
You and your sisters who go 
    with you should have hasten to include your sister in this  righteous act 
    that you are doing, even if you did not owe her a favour for driving you. 
    This is part of loving good for the Muslims and the duty of spreading good 
    among the people. 
If you did not do that and 
    she is eager for the good that you have, there is nothing wrong with her 
    stipulating this benefit in return for driving you, although it would have 
    been better in her case to do that sincerely for the sake of Allah alone 
    rather than asking you for something. She should strive to do righteous 
    deeds and attend the lessons with you as if she is one of you. That would 
    combine two good things, helping her sisters to do something good and 
    seeking reward for it with Allah, as well as attaining the same benefits as 
    you. 
If her circumstances do not 
    allow that and she needs help from you, then you should give her this help 
    and there is nothing wrong with her asking for it from you. 
And Allah knows best.