May Allah grant long life to your mother.
If you consider the town of your mother as your home town then yes then you have to pray full and observe the fast also. If you are not considering that place as your watan then your namaz and roza will be Qasr if you are planing to stay for 9 days and less.
Spend more time with your mother stay for 10 days then pray full and fast.
Syed Abul Qasim Rizvi
Are you able to fast if your mother lives in another city compare to you, but you go to see her within the month of Ramadan, will you be able to hold fast while you are at your mother’s house?