US citizenship claim

My mum in-law(85years) has been out of the US for a while( over 8years) now following the news of her husband's demise, for which she had to return to Nigeria and has since been battling health challenges. She had however filed an immigrant case for my husband which is due but on hold as she does not wish to go back due to old age and health challenges. Please an advice is needed on what to do.