Is it permissible for my deceased parents to use the money designated for charitable work for their son in building or tiling a portion of their house?

If the parents are poor and need to build and tile [their home], there is a difference of opinion among scholars regarding the permissibility of taking from charity funds for this purpose. The more cautious approach for them is to guarantee the money. However, if they are rich or do not have an essential need for it, then they have erred in spending the money for their own benefit. They must guarantee the money and spend it for its designated purpose, unless they seek permission from the donors and they agree to it.