Okay, I have broadband 50. Its like a super fast internet in my area. My mother watches series online by streaming them. How do I limit the bandwidth or connection speed on my mothers computer? Are there any programs out there that can help me with my problem?
Some routers are capable of doing what you speak of, usually only the higher end models have this feature though. Luckily, there are some custom firmwares for lower end routers which enable this. As for software, I don't know any off the top of my head. If you wish to search, the term is "traffic shaping".
As ThatGuy eluded to, see if can flash your router's firmware to Tomato or DD-WRT. This will allow you to allocate less bandwidth to your mom's shows. Also, don't forget to try just rebooting your router and modem.