She is helping her parents from her salary without her husband’s knowledge
Question

                I am a married woman with three children. I work in a company and I get a monthly salary from which I contribute to household expenses, i.e., I help my husband. My question is: my father is 84 years old and my mother is 76, and I am their only daughter. I help them from my monthly salary without my husband’s knowledge, even though he would not object to that. What is the Islamic ruling on that?.
Praise be to Allah.If there was no condition 
    stipulated by your husband that you may work provided you spend all or part 
    of your salary on household expenses, then the salary that you get or the 
    amount that is left after you pay the amount that your husband stipulated 
    you should pay, is your property and it is permissible for you to spend it 
    in any way that is halaal, and you do not have to ask your husband’s 
    permission with regard to that. But if you do that so as show respect to 
    him, that is better. 
Helping one’s parents is 
    one of the greatest acts of kindness and goodness, and it comes under the 
    heading of upholding ties of kinship that increases one’s lifespan and 
    brings blessing in one's provision, as the Prophet  (peace and blessings 
    of Allaah be upon him) said: “Whoever would like his rizq (provision) to be 
    increased and his life to be extended, should uphold the ties of kinship.” 
    Narrated by al-Bukhaari (5986) and Muslim (2557).  
Based on that, there is 
    nothing wrong with what you are doing by helping your parents with part of 
    your salary without your husband’s knowledge, especially since you say that 
    he does not mind, but if you think that telling him will make him feel 
    respected, then that is better. 
We ask Allaah to reward you 
    for this help and to bless your wealth and your work for you. 
And Allaah knows best.