According to Adobe, the minimum requirement for watching HD video is an Intel Core Duo 1.8GHz. The Core i3 processor is so much better and newer than the Core Duo that it's hard to find comparisons between them. The Core i3 is two CPU generations newer, so it's definitely well above the minimum requirements. Check the following models out. But upgrade the rams to 8gb will be better for option 2 and 3.
1. Dell Vostro 14 5480-00452G-W8 Laptop/ Notebook (i3-4005U, 500GB, 8GB Cache, 4GB, NV 830M, Windows 8.1, 1.54kg) RM2,100/-
2. Dell Vostro 14 5480-0045SG-W8 Laptop/ Notebook (i3-4005U, 500GB, 4GB, Intel, Windows 8.1, 1.54kg) RM1,906/-
3. Dell Inspiron 14 5458-20452G-W8 Laptop/ Notebook (i5-5200U, 500GB, 4GB, NV 920M, Windows 8.1, 2kg) RM2,237/-
Choice 1 and 2 are both weighed 1.54kg only. I presume your mum wouldn't want a heavy and energy consuming laptop. But you can consider option 3 too. Chekc them out.

Cool, thanks.
Though if i saw correctly, Vostro usually comes with 1 year warranty while Inspiron comes with 2.
Cheapest Inspiron i could find is inspiron-14-5458, it's i3 with 4Gb ram priced at Rm1849.