Yes you can choose Mtech in a different branch and stream.

Civil and electronic can prove to be better branches of engineering.
You can choose electronics though.
But no doubt it also depends upon your interest as well.

SCOPE OF CIVIL ENGINEERING

• The construction and infrastructural development projects including town planning are on the rise in the coming days and will demand more domain specialists.
• In search of comfortably safe homes, better roads and standardised living, the demand for civil engineers are to raise more.

SCOPE OF ELECTRICAL ENGINEERING

• Electrical engineering is rapidly growing not only within core areas such as wireless communications and mobile technologies but also in other cross-functioning areas including nanotechnology and biomedical engineering.
• The world is moving towards the renewable source of energy including hydel, solar and wind power, and multi-national corporations are searching for power generation experts.

Hope it helps you in future.
Good luck.