Switching between new and old regime

I wanted to know if in my and mothers case we will be able to switch between new and old regime next year. 

1) Me - I have filed return as per old regime for AY 21-22 as a salaried person . I understand salaried person can switch between new and old regime freely. However i have been unemployed since April 21. So will i be able to file tax for AY 22-23 as per new regime? 

2) My mother is a senior citizen and has been a house wife all her life. Her income is from share dividend. She has filed return for AY 21-22 as per old regime. Can she file as per new regime next year. 

In case any one of us cannot file return as per new regime can i revise my return for AY 21-22 to new regime now?