Welcome to the forum from me too
@mumhasdementia you'll find lots of advice and support here. As karaokePete has posted, asking to go home is likely to be a place/time where the person felt 'safe', not necessarily their last home, sometimes to a childhood home. The compassionate communication thread has some useful suggestions which may help. When my mum was asking to go home it was a phase that didn't last very long but saying something like 'maybe tomorrow if the weather's better' or 'it's a bit late now, it will be dark soon' and trying a distraction usually worked. It's hard at the moment due to the visiting restrictions/infection control in care homes but maybe you could suggest a cup of tea, or something else that might distract - perhaps enlist one of the carers to get your mum a drink or a biscuit if she starts asking to go home? I've started taking a book in when visiting mum and I read her some short stories or poems and it helps to give the visit more of a focus rather than just me sitting there trying to think of things to say.
Has your mum been in the home long? If not then it can take some time to settle in to the new surroundings/routines and that may be making your mum anxious. Also, those with dementia pick up very easily on how others are feelings. If I feel stressed/anxious my mum feels the same as she really picks up on my emotions, speech and body language. As hard as it may feel sometimes, I always go to the visits with a big smile on my face and say positive things like how lovely she looks, how nice the home is etc and it really seems to help, so maybe worth a try with your mum.