Is it permissible for a woman observing the 'iddah (waiting period) after her husband's death to stay in the hospital with her very ill daughter and spend the night there?

A woman whose husband has died must remain in her home for the duration of her 'iddah (waiting period). This is what the Messenger of Allah, peace and blessings be upon him, decreed, and the Companions and jurists followed suit. She is permitted to go out during the day for a necessity, but she is not permitted to go out at night or spend the night outside her home, except in cases of extreme necessity, such as if her daughter is ill and there is no one else to care for her.