How can we divert dad's attention kindly?

Dad recently had to go into memory care and won't talk about anything else but leaving.  My father was diagnosed with early onset alzheimers and was living at home until recently. My mother (primary caregiver) would not retire early and is still working full time. Being left alone all day was becoming too much for him, he was getting very angry with her being gone and asked to go into assisted living. We moved him in at the beginning of June. He left one day and got lost, my mom picked him up and brought him back. Last week he did it again, but this time he was brought back to the center by the police and we've put him into memory care for his safe being. I know he will continue to wonder despite his pleas that he won't and it is for the best to have him in there. However, he is still physically fit and the only thing he likes to do it walk - he wants to be outside. The staff go outside and walk with him during the day, but obviously he isnt' free to come and go as he pleases anymore due to the incident. We don't have even a minute free during out visits with him since that he isn't begging, pleading or yelling to get out and 'be free.' Most of the residents in memory care are for more advanced then him and sleep most of the day or are not mobile so he is lonely with no one to talk to and no ability to go out and walk as he pleases. I understand his pleas, but know he has to stay. However, this is so hard on my mother and myself when we visit since the whole time it's asking to come home or get out. My mother can't cope and doesn't even want to go see him anymore. Redirecting his attention doesn't work for more than a couple seconds/minutes at best. Does anyone have any thoughts or advice on how to react/respond to his pleas or how to better redirect his attention? His tears are unbearable. Please and thank you.