Committing zina with one's autistic brother

Q: When my friend was 10 and 13 she tried committing zina with her autistic brother. She believes that at the time she didn't know what this action was. Her brother has been tested to have no sexual fantasies. She believes that the penis did not penetrate the vagina, which means this is not intercourse. She has repented and 100% knows she won't do it again. She still feels guilty, does she have to leave home, where would she go? She doesn't want to reveal this to her family. 

Status of our currency

Q: What is the status of our currency i.e. rands and dollars? Is it thaman (money) or mabee’ (sale commodity)? In other words, what is the Islamic position on fiat money which is the currency of the majority of the world today? Some say that it is haraam and riba as the money of the Quraan Majeed and Sunnah is gold dinars and silver dirhams which have “intrinsic value”, while today’s money is backed by interest. What is the proof in the Quraan Majeed and Sunnah?

Woman refusing to go for umrah with her brother

Q: My mother in law has been asked by her brothers to go for Umrah with them (they will pay all the expenses) but she refuses saying that she will go for Umrah only with her sons (they dont have enough money at this point in their lives). She says that she doesn't want any favours.

The question is, is she allowed to refuse Umrah? Would it be a sin? Or can she wait for her sons to take her to Makkah.

Living in one's parents house after their demise

Q: If a person is living in his parents house and he has no resources to live somewhere else, so is it necessary in Islam to sell his parents house after their death? If he doesnt do that before getting financially stable, is there anything that his mother or father are getting gunah in the other world? I want to sell the house after some time just to ensure my mother or father is not getting any gunah for this? All my siblings have no problem with me living in the house.