Synonyms

Parsimony means "extreme or excessive economy or frugality or stinginess".

Ebullient means "overflowing with fervour" or "excited". 

Yes, it is correct. Surge is a sudden powerful forward or upward movement, especially by a crowd or by a natural force, such as the tide. This is perfect synonym of undulate.

Gogitate means to think deeply. So, only speculate which means to think deeply about various aspects or meditate is the correct answer. Contrive means to design or invent and is incorrect. 

Something that is done covertly is done in a manner that is not in plain sight. Hence, hidden is correct.

'Churlish' means 'rude in a mean-spirited way'. 

'Convivial' means 'friendly, lively and enjoyable'. Hence, option (4) is the correct answer. 

'Halt' means 'bring or come to an abrupt stop'. 'Pause' means 'interrupt action or speech briefly'. Thus, synonym of 'halt' is 'pause'. 

 Conjecture means an opinion or conclusion formed on the basis of incomplete information. It is synonymous to "guess".

'Cajole' means 'persuade to do something'. 'Coax' means 'persuade someone gradually or gently to do something'. 

Compunction means deep regret or remorse.

Grain means small, hard seed or seedlike fruit, esp. that of any cereal plant, as wheat, rice, corn, rye, etc. Hence, option 3.

Frugality means not wasteful; not spending freely or unnecessarily; thrifty; economical. Option 4 is the perfect synonym.

A 'foray' means a sudden attack or incursion into enemy territory, or more generally, an attempt or venture into something new. 'Venture' best captures this meaning of undertaking a risky or daring activity.

Garrulous means a person talking much or too much, esp. about unimportant things. Loquacious means very talkative.