Can a Muslim mom leave her wealth to charity with daughters’ consent?

Assalamualaikum Brother A friends mom want to write a will and give away all her wealth to a cancer charity in canada.The whole family is muslim. She has three daughters aged 22, 20 and 7. My question is that can the mother give away all her wealth in charity after she dies or even while she is alive? If the mother has permission of her two adult daughters, can she give it away then, minus the share of the little sister? Would it be okay for a muslim lady to give everything to a charity in canada instead of helping people here in pakistan where she normally resides? Is it okay for Muslims to give charity to christian or any other organisations besides muslims’? If the mother does write this will and give away everything to this cancer charity in canada without consulting with her daughters, would she be held accountable on the day of judgement, i mean is that a sin? Also please keep in mind that her husband is well off too and the mom generally has a tendency to help the needy, so please let me know whats the best possible option for her knowing that she has always wanted to help the poor and the needy. Wasalaaam